diff --git a/src/main/java/com/sofa/linkiving/domain/link/controller/LinkApi.java b/src/main/java/com/sofa/linkiving/domain/link/controller/LinkApi.java
index d7213448..fa4a2508 100644
--- a/src/main/java/com/sofa/linkiving/domain/link/controller/LinkApi.java
+++ b/src/main/java/com/sofa/linkiving/domain/link/controller/LinkApi.java
@@ -7,12 +7,14 @@
 import com.sofa.linkiving.domain.link.dto.request.LinkTitleUpdateReq;
 import com.sofa.linkiving.domain.link.dto.request.LinkUpdateReq;
 import com.sofa.linkiving.domain.link.dto.request.MetaScrapeReq;
+import com.sofa.linkiving.domain.link.dto.request.SummaryUpdateReq;
 import com.sofa.linkiving.domain.link.dto.response.LinkCardsRes;
 import com.sofa.linkiving.domain.link.dto.response.LinkDetailRes;
 import com.sofa.linkiving.domain.link.dto.response.LinkDuplicateCheckRes;
 import com.sofa.linkiving.domain.link.dto.response.LinkRes;
 import com.sofa.linkiving.domain.link.dto.response.MetaScrapeRes;
 import com.sofa.linkiving.domain.link.dto.response.RecreateSummaryResponse;
+import com.sofa.linkiving.domain.link.dto.response.SummaryRes;
 import com.sofa.linkiving.domain.link.enums.Format;
 import com.sofa.linkiving.domain.member.entity.Member;
 import com.sofa.linkiving.global.common.BaseResponse;
@@ -98,4 +100,11 @@ BaseResponse<RecreateSummaryResponse> recreateSummary(
 		@Valid Format format,
 		Member member
 	);
+
+	@Operation(summary = "새로운 요약 선택", description = "신규 요약으로 요약 내용을 수정합니다.")
+	BaseResponse<SummaryRes> updateSummary(
+		Long id,
+		@Valid SummaryUpdateReq request,
+		Member member
+	);
 }
diff --git a/src/main/java/com/sofa/linkiving/domain/link/controller/LinkController.java b/src/main/java/com/sofa/linkiving/domain/link/controller/LinkController.java
index 408180ae..85371b40 100644
--- a/src/main/java/com/sofa/linkiving/domain/link/controller/LinkController.java
+++ b/src/main/java/com/sofa/linkiving/domain/link/controller/LinkController.java
@@ -16,12 +16,14 @@
 import com.sofa.linkiving.domain.link.dto.request.LinkTitleUpdateReq;
 import com.sofa.linkiving.domain.link.dto.request.LinkUpdateReq;
 import com.sofa.linkiving.domain.link.dto.request.MetaScrapeReq;
+import com.sofa.linkiving.domain.link.dto.request.SummaryUpdateReq;
 import com.sofa.linkiving.domain.link.dto.response.LinkCardsRes;
 import com.sofa.linkiving.domain.link.dto.response.LinkDetailRes;
 import com.sofa.linkiving.domain.link.dto.response.LinkDuplicateCheckRes;
 import com.sofa.linkiving.domain.link.dto.response.LinkRes;
 import com.sofa.linkiving.domain.link.dto.response.MetaScrapeRes;
 import com.sofa.linkiving.domain.link.dto.response.RecreateSummaryResponse;
+import com.sofa.linkiving.domain.link.dto.response.SummaryRes;
 import com.sofa.linkiving.domain.link.enums.Format;
 import com.sofa.linkiving.domain.link.facade.LinkFacade;
 import com.sofa.linkiving.domain.member.entity.Member;
@@ -152,4 +154,15 @@ public BaseResponse<RecreateSummaryResponse> recreateSummary(
 		RecreateSummaryResponse response = linkFacade.recreateSummary(member, id, format);
 		return BaseResponse.success(response, "요약 재성성 완료");
 	}
+
+	@Override
+	@PatchMapping("/{id}/summary")
+	public BaseResponse<SummaryRes> updateSummary(
+		@PathVariable Long id,
+		@RequestBody SummaryUpdateReq request,
+		@AuthMember Member member
+	) {
+		SummaryRes response = linkFacade.updateSummary(id, member, request.summary(), request.format());
+		return BaseResponse.success(response, "요약 수정 완료");
+	}
 }
diff --git a/src/main/java/com/sofa/linkiving/domain/link/dto/request/SummaryUpdateReq.java b/src/main/java/com/sofa/linkiving/domain/link/dto/request/SummaryUpdateReq.java
new file mode 100644
index 00000000..a6cb5a0c
--- /dev/null
+++ b/src/main/java/com/sofa/linkiving/domain/link/dto/request/SummaryUpdateReq.java
@@ -0,0 +1,16 @@
+package com.sofa.linkiving.domain.link.dto.request;
+
+import com.sofa.linkiving.domain.link.enums.Format;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.NotNull;
+
+public record SummaryUpdateReq(
+	@NotNull(message = "요약 내용은 필수입니다.")
+	@Schema(description = "요약 내용", example = "새롭게 선택한 요약 내용")
+	String summary,
+	@NotNull(message = "요약 포맷 정보는 필수입니다.")
+	@Schema(description = "요약 포맷 정보 (CONCISE, DETAILED)", example = "CONCISE")
+	Format format
+) {
+}
diff --git a/src/main/java/com/sofa/linkiving/domain/link/dto/response/LinkDetailRes.java b/src/main/java/com/sofa/linkiving/domain/link/dto/response/LinkDetailRes.java
index 200346a6..91dcf443 100644
--- a/src/main/java/com/sofa/linkiving/domain/link/dto/response/LinkDetailRes.java
+++ b/src/main/java/com/sofa/linkiving/domain/link/dto/response/LinkDetailRes.java
@@ -40,17 +40,4 @@ public static LinkDetailRes of(Link link, Summary summary) {
 		);
 	}
 
-	public record SummaryRes(
-		@Schema(description = "요약 ID")
-		Long id,
-		@Schema(description = "요약 내용", example = "이 링크는 예시 링크입니다.")
-		String content
-	) {
-		public static SummaryRes from(Summary summary) {
-			if (summary == null) {
-				return null;
-			}
-			return new SummaryRes(summary.getId(), summary.getContent());
-		}
-	}
 }
diff --git a/src/main/java/com/sofa/linkiving/domain/link/dto/response/SummaryRes.java b/src/main/java/com/sofa/linkiving/domain/link/dto/response/SummaryRes.java
new file mode 100644
index 00000000..4d00d62c
--- /dev/null
+++ b/src/main/java/com/sofa/linkiving/domain/link/dto/response/SummaryRes.java
@@ -0,0 +1,19 @@
+package com.sofa.linkiving.domain.link.dto.response;
+
+import com.sofa.linkiving.domain.link.entity.Summary;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+public record SummaryRes(
+	@Schema(description = "요약 ID")
+	Long id,
+	@Schema(description = "요약 내용", example = "이 링크는 예시 링크입니다.")
+	String content
+) {
+	public static SummaryRes from(Summary summary) {
+		if (summary == null) {
+			return null;
+		}
+		return new SummaryRes(summary.getId(), summary.getContent());
+	}
+}
diff --git a/src/main/java/com/sofa/linkiving/domain/link/facade/LinkFacade.java b/src/main/java/com/sofa/linkiving/domain/link/facade/LinkFacade.java
index 2bd06075..1149f4d7 100644
--- a/src/main/java/com/sofa/linkiving/domain/link/facade/LinkFacade.java
+++ b/src/main/java/com/sofa/linkiving/domain/link/facade/LinkFacade.java
@@ -13,7 +13,9 @@
 import com.sofa.linkiving.domain.link.dto.response.LinkRes;
 import com.sofa.linkiving.domain.link.dto.response.MetaScrapeRes;
 import com.sofa.linkiving.domain.link.dto.response.RecreateSummaryResponse;
+import com.sofa.linkiving.domain.link.dto.response.SummaryRes;
 import com.sofa.linkiving.domain.link.entity.Link;
+import com.sofa.linkiving.domain.link.entity.Summary;
 import com.sofa.linkiving.domain.link.enums.Format;
 import com.sofa.linkiving.domain.link.service.LinkService;
 import com.sofa.linkiving.domain.link.service.SummaryService;
@@ -82,7 +84,7 @@ public RecreateSummaryResponse recreateSummary(Member member, Long linkId, Forma
 		String url = linkService.getLink(linkId, member).getUrl();
 
 		String existingSummary = summaryService.getSummary(linkId).getContent();
-		String newSummary = summaryService.createSummary(linkId, url, format);
+		String newSummary = summaryService.initialSummary(linkId, url, format);
 
 		String comparison = summaryService.comparisonSummary(existingSummary, newSummary);
 
@@ -98,4 +100,11 @@ public MetaScrapeRes scrapeMetadata(String url) {
 		OgTagDto ogTag = ogTagCrawler.crawl(url);
 		return MetaScrapeRes.from(ogTag);
 	}
+
+	public SummaryRes updateSummary(Long id, Member member, String content, Format format) {
+		Link link = linkService.getLink(id, member);
+		Summary summary = summaryService.createSummary(link, format, content);
+		summaryService.selectSummary(link.getId(), summary.getId());
+		return SummaryRes.from(summary);
+	}
 }
diff --git a/src/main/java/com/sofa/linkiving/domain/link/service/SummaryCommandService.java b/src/main/java/com/sofa/linkiving/domain/link/service/SummaryCommandService.java
index 9af98652..3d392f02 100644
--- a/src/main/java/com/sofa/linkiving/domain/link/service/SummaryCommandService.java
+++ b/src/main/java/com/sofa/linkiving/domain/link/service/SummaryCommandService.java
@@ -2,6 +2,9 @@
 
 import org.springframework.stereotype.Service;
 
+import com.sofa.linkiving.domain.link.entity.Link;
+import com.sofa.linkiving.domain.link.entity.Summary;
+import com.sofa.linkiving.domain.link.enums.Format;
 import com.sofa.linkiving.domain.link.error.LinkErrorCode;
 import com.sofa.linkiving.domain.link.repository.SummaryRepository;
 import com.sofa.linkiving.global.error.exception.BusinessException;
@@ -24,5 +27,15 @@ public void selectSummary(Long linkId, Long summaryId) {
 			throw new BusinessException(LinkErrorCode.SUMMARY_NOT_FOUND);
 		}
 	}
+
+	public Summary save(Link link, Format format, String content) {
+		return summaryRepository.save(
+			Summary.builder()
+				.link(link)
+				.format(format)
+				.content(content)
+				.build()
+		);
+	}
 }
 
diff --git a/src/main/java/com/sofa/linkiving/domain/link/service/SummaryService.java b/src/main/java/com/sofa/linkiving/domain/link/service/SummaryService.java
index f867945a..f92a96c0 100644
--- a/src/main/java/com/sofa/linkiving/domain/link/service/SummaryService.java
+++ b/src/main/java/com/sofa/linkiving/domain/link/service/SummaryService.java
@@ -3,6 +3,7 @@
 import org.springframework.stereotype.Service;
 
 import com.sofa.linkiving.domain.link.ai.AiSummaryClient;
+import com.sofa.linkiving.domain.link.entity.Link;
 import com.sofa.linkiving.domain.link.entity.Summary;
 import com.sofa.linkiving.domain.link.enums.Format;
 
@@ -12,9 +13,10 @@
 @RequiredArgsConstructor
 public class SummaryService {
 	private final SummaryQueryService summaryQueryService;
+	private final SummaryCommandService summaryCommandService;
 	private final AiSummaryClient aiSummaryClient;
 
-	public String createSummary(Long linkId, String url, Format format) {
+	public String initialSummary(Long linkId, String url, Format format) {
 		return aiSummaryClient.generateSummary(linkId, url, format);
 	}
 
@@ -25,4 +27,12 @@ public String comparisonSummary(String existingSummary, String newSummary) {
 	public Summary getSummary(Long linkId) {
 		return summaryQueryService.getSummary(linkId);
 	}
+
+	public Summary createSummary(Link link, Format format, String content) {
+		return summaryCommandService.save(link, format, content);
+	}
+
+	public void selectSummary(Long linkId, Long summaryId) {
+		summaryCommandService.selectSummary(linkId, summaryId);
+	}
 }
diff --git a/src/test/java/com/sofa/linkiving/domain/link/facade/LinkFacadeTest.java b/src/test/java/com/sofa/linkiving/domain/link/facade/LinkFacadeTest.java
index 9280a7ba..3814829d 100644
--- a/src/test/java/com/sofa/linkiving/domain/link/facade/LinkFacadeTest.java
+++ b/src/test/java/com/sofa/linkiving/domain/link/facade/LinkFacadeTest.java
@@ -116,7 +116,7 @@ void shouldReturnRecreateSummaryResponseWhenRecreateSummary() {
 		given(summaryService.getSummary(linkId)).willReturn(mockSummary);
 
 		// 3. SummaryService (새 요약 생성 및 비교)
-		given(summaryService.createSummary(linkId, url, format)).willReturn(newSummaryBody);
+		given(summaryService.initialSummary(linkId, url, format)).willReturn(newSummaryBody);
 		given(summaryService.comparisonSummary(existingSummaryBody, newSummaryBody)).willReturn(comparisonBody);
 
 		// when
@@ -130,7 +130,7 @@ void shouldReturnRecreateSummaryResponseWhenRecreateSummary() {
 
 		// verify
 		verify(summaryService).getSummary(linkId);
-		verify(summaryService).createSummary(linkId, url, format);
+		verify(summaryService).initialSummary(linkId, url, format);
 		verify(summaryService).comparisonSummary(existingSummaryBody, newSummaryBody);
 	}
 
diff --git a/src/test/java/com/sofa/linkiving/domain/link/integration/LinkApiIntegrationTest.java b/src/test/java/com/sofa/linkiving/domain/link/integration/LinkApiIntegrationTest.java
index 5cd644f7..920dd5a8 100644
--- a/src/test/java/com/sofa/linkiving/domain/link/integration/LinkApiIntegrationTest.java
+++ b/src/test/java/com/sofa/linkiving/domain/link/integration/LinkApiIntegrationTest.java
@@ -28,6 +28,7 @@
 import com.sofa.linkiving.domain.link.dto.request.LinkTitleUpdateReq;
 import com.sofa.linkiving.domain.link.dto.request.LinkUpdateReq;
 import com.sofa.linkiving.domain.link.dto.request.MetaScrapeReq;
+import com.sofa.linkiving.domain.link.dto.request.SummaryUpdateReq;
 import com.sofa.linkiving.domain.link.entity.Link;
 import com.sofa.linkiving.domain.link.entity.Summary;
 import com.sofa.linkiving.domain.link.enums.Format;
@@ -724,4 +725,29 @@ void shouldFailWhenMetaScrapeUrlIsMissing() throws Exception {
 			)
 			.andExpect(status().isBadRequest());
 	}
+
+	@Test
+	@DisplayName("updateSummary API: PATCH 요청 시 요약 정보를 수정하고 200 OK를 반환한다")
+	void updateSummaryApi_ShouldReturn200Ok() throws Exception {
+		// given
+		Link savedLink = linkRepository.save(Link.builder()
+			.member(testMember)
+			.url("https://example.com/article")
+			.title("테스트 링크")
+			.build());
+		Long linkId = savedLink.getId();
+
+		SummaryUpdateReq request = new SummaryUpdateReq("수정된 요약 텍스트", Format.DETAILED);
+
+		// when & then
+		mockMvc.perform(patch(BASE_URL + "/{id}/summary", linkId)
+				.contentType(MediaType.APPLICATION_JSON)
+				.content(objectMapper.writeValueAsString(request))
+				.with(csrf())
+				.with(user(testUserDetails))
+			)
+			.andExpect(status().isOk())
+			.andExpect(jsonPath("$.message").value("요약 수정 완료"))
+			.andExpect(jsonPath("$.data.content").value("수정된 요약 텍스트"));
+	}
 }
diff --git a/src/test/java/com/sofa/linkiving/domain/link/repository/SummaryRepositoryTest.java b/src/test/java/com/sofa/linkiving/domain/link/repository/SummaryRepositoryTest.java
index b827d515..02af0929 100644
--- a/src/test/java/com/sofa/linkiving/domain/link/repository/SummaryRepositoryTest.java
+++ b/src/test/java/com/sofa/linkiving/domain/link/repository/SummaryRepositoryTest.java
@@ -3,6 +3,7 @@
 import static org.assertj.core.api.Assertions.*;
 
 import java.util.List;
+import java.util.Optional;
 
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
@@ -13,6 +14,7 @@
 
 import com.sofa.linkiving.domain.link.entity.Link;
 import com.sofa.linkiving.domain.link.entity.Summary;
+import com.sofa.linkiving.domain.link.enums.Format;
 import com.sofa.linkiving.domain.member.entity.Member;
 
 @DataJpaTest
@@ -119,4 +121,65 @@ void shouldReturnEmptyWhenLinkListIsEmpty() {
 		// then
 		assertThat(result).isEmpty();
 	}
+
+	@Test
+	@DisplayName("clearSelectedByLinkId 및 selectByIdAndLinkId 실행 시 selected 요약이 단 1개만 존재한다")
+	void shouldEnsureOnlyOneSummaryIsSelected() {
+		// given
+		Member member = Member.builder()
+			.email("test@test.com")
+			.password("pw")
+			.build();
+		em.persist(member);
+		Link link = Link.builder()
+			.member(member)
+			.url("http://test.com")
+			.title("t1")
+			.build();
+		em.persist(link);
+
+		// 1. 과거 요약 1 (기존 선택됨)
+		Summary oldSummary1 = Summary.builder()
+			.link(link)
+			.content("과거 요약 1")
+			.format(Format.CONCISE)
+			.selected(true)
+			.build();
+
+		// 2. 과거 요약 2 (선택 안됨)
+		Summary oldSummary2 = Summary.builder()
+			.link(link)
+			.content("과거 요약 2")
+			.format(Format.DETAILED)
+			.selected(false)
+			.build();
+
+		// 3. 방금 새로 수정한 요약 (아직 선택 안됨)
+		Summary newSummary = Summary.builder()
+			.link(link)
+			.content("새로 수정한 요약")
+			.format(Format.DETAILED).selected(false)
+			.build();
+
+		em.persist(oldSummary1);
+		em.persist(oldSummary2);
+		em.persist(newSummary);
+
+		// when - Service 계층에서 수행하는 두 가지 쿼리를 순서대로 실행
+
+		summaryRepository.clearSelectedByLinkId(link.getId());
+		summaryRepository.selectByIdAndLinkId(newSummary.getId(), link.getId());
+
+		// then
+		Optional<Summary> selectedSummary = summaryRepository.findByLinkIdAndSelectedTrue(link.getId());
+		assertThat(selectedSummary).isPresent();
+		assertThat(selectedSummary.get().getId()).isEqualTo(newSummary.getId());
+
+		long selectedCount = summaryRepository.findAll().stream()
+			.filter(s -> s.getLink().getId().equals(link.getId()))
+			.filter(Summary::isSelected)
+			.count();
+
+		assertThat(selectedCount).isEqualTo(1L);
+	}
 }
diff --git a/src/test/java/com/sofa/linkiving/domain/link/service/SummaryServiceTest.java b/src/test/java/com/sofa/linkiving/domain/link/service/SummaryServiceTest.java
index 0ef8695f..16e125b8 100644
--- a/src/test/java/com/sofa/linkiving/domain/link/service/SummaryServiceTest.java
+++ b/src/test/java/com/sofa/linkiving/domain/link/service/SummaryServiceTest.java
@@ -26,8 +26,8 @@ public class SummaryServiceTest {
 	private AiSummaryClient aiSummaryClient;
 
 	@Test
-	@DisplayName("createSummary 호출 시 AiSummaryClient에게 위임한다")
-	void shouldCallGenerateSummaryWhenCreateSummary() {
+	@DisplayName("generateSummary 호출 시 SummaryClient에게 위임한다")
+	void shouldCallGenerateSummaryWhenInitialSummary() {
 		// given
 		Long linkId = 1L;
 		String url = "https://example.com";
@@ -37,7 +37,7 @@ void shouldCallGenerateSummaryWhenCreateSummary() {
 		given(aiSummaryClient.generateSummary(linkId, url, format)).willReturn(expectedResult);
 
 		// when
-		String result = summaryService.createSummary(linkId, url, format);
+		String result = summaryService.initialSummary(linkId, url, format);
 
 		// then
 		assertThat(result).isEqualTo(expectedResult);