diff --git a/Sources/WebAuthn/Ceremonies/Registration/AttestationObject.swift b/Sources/WebAuthn/Ceremonies/Registration/AttestationObject.swift
index bd32cc1..0ae7e95 100644
--- a/Sources/WebAuthn/Ceremonies/Registration/AttestationObject.swift
+++ b/Sources/WebAuthn/Ceremonies/Registration/AttestationObject.swift
@@ -22,6 +22,13 @@ public struct AttestationObject: Sendable {
     let format: AttestationFormat
     let attestationStatement: CBOR
 
+    /// The Authenticator Attestation Globally Unique Identifier (AAGUID) from the attestation object.
+    /// Returns nil if attested credential data is not present.
+    /// - SeeAlso: [WebAuthn Level 3 Editor's Draft §6.5.1. Attested Credential Data](https://w3c.github.io/webauthn/#sctn-attested-credential-data)
+    public var aaguid: AAGUID? {
+        authenticatorData.attestedData?.authenticatorAttestationGUID
+    }
+
     func verify(
         relyingPartyID: String,
         verificationRequired: Bool,
diff --git a/Sources/WebAuthn/Ceremonies/Registration/Credential.swift b/Sources/WebAuthn/Ceremonies/Registration/Credential.swift
index ca669f2..372d75d 100644
--- a/Sources/WebAuthn/Ceremonies/Registration/Credential.swift
+++ b/Sources/WebAuthn/Ceremonies/Registration/Credential.swift
@@ -43,4 +43,11 @@ public struct Credential: Sendable {
     public let attestationObject: AttestationObject
 
     public let attestationClientDataJSON: CollectedClientData
+
+    /// The Authenticator Attestation Globally Unique Identifier (AAGUID) from the attestation object.
+    /// Returns nil if attested credential data is not present.
+    /// - SeeAlso: [WebAuthn Level 3 Editor's Draft §6.5.1. Attested Credential Data](https://w3c.github.io/webauthn/#sctn-attested-credential-data)
+    public var aaguid: AAGUID? {
+        attestationObject.aaguid
+    }
 }
diff --git a/Tests/WebAuthnTests/WebAuthnManagerRegistrationTests.swift b/Tests/WebAuthnTests/WebAuthnManagerRegistrationTests.swift
index 4efd893..a724941 100644
--- a/Tests/WebAuthnTests/WebAuthnManagerRegistrationTests.swift
+++ b/Tests/WebAuthnTests/WebAuthnManagerRegistrationTests.swift
@@ -403,6 +403,71 @@ struct WebAuthnManagerRegistrationTests {
         #expect(credential.publicKey == credentialPublicKey)
     }
     
+    @Test(arguments: [
+        TestKeyConfiguration.ecdsa,
+        TestKeyConfiguration.rsa,
+    ])
+    func credentialAAGUIDAccessorReturnsCorrectValue(keyConfiguration: TestKeyConfiguration) async throws {
+        let testAAGUID = AAGUID(uuidString: "dd4ec289-e01d-41c9-bb89-70fa845d4bf2")!
+        let credentialID: [UInt8] = [0, 1, 0, 1, 0, 1]
+        let credentialPublicKey: [UInt8] = keyConfiguration.credentialPublicKey
+        let authData = keyConfiguration.authDataBuilder
+            .attestedCredData(
+                authenticatorAttestationGUID: testAAGUID,
+                credentialPublicKey: credentialPublicKey
+            )
+            .noExtensionData()
+        let attestationObject = keyConfiguration.attestationObjectBuilder
+            .authData(authData)
+            .build()
+            .cborEncoded
+
+        let credential = try await finishRegistration(
+            rawID: credentialID,
+            attestationObject: attestationObject
+        )
+
+        // Test that credential.aaguid returns the correct AAGUID
+        #expect(credential.aaguid != nil)
+        #expect(credential.aaguid?.id == testAAGUID.id)
+        #expect(credential.aaguid?.bytes == testAAGUID.bytes)
+        
+        // Test that credential.attestationObject.aaguid returns the same value
+        #expect(credential.attestationObject.aaguid != nil)
+        #expect(credential.attestationObject.aaguid?.id == testAAGUID.id)
+        #expect(credential.attestationObject.aaguid?.bytes == testAAGUID.bytes)
+        
+        // Verify they return the same value
+        #expect(credential.aaguid == credential.attestationObject.aaguid)
+    }
+    
+    @Test(arguments: [
+        TestKeyConfiguration.ecdsa,
+        TestKeyConfiguration.rsa,
+    ])
+    func credentialAAGUIDAccessorReturnsAnonymousByDefault(keyConfiguration: TestKeyConfiguration) async throws {
+        // When no AAGUID is specified, it defaults to .anonymous
+        let credentialID: [UInt8] = [0, 1, 0, 1, 0, 1]
+        let credentialPublicKey: [UInt8] = keyConfiguration.credentialPublicKey
+        let authData = keyConfiguration.authDataBuilder
+            .attestedCredData(credentialPublicKey: credentialPublicKey) // Uses .anonymous by default
+            .noExtensionData()
+        let attestationObject = keyConfiguration.attestationObjectBuilder
+            .authData(authData)
+            .build()
+            .cborEncoded
+
+        let credential = try await finishRegistration(
+            rawID: credentialID,
+            attestationObject: attestationObject
+        )
+
+        // Test that credential.aaguid returns the anonymous AAGUID
+        #expect(credential.aaguid != nil)
+        #expect(credential.aaguid == .anonymous)
+        #expect(credential.aaguid?.bytes == Array(repeating: 0, count: 16))
+    }
+    
     @Test
     func finishRegistrationFuzzying() async throws {
         for _ in 1...50 {