diff --git a/DevLog/Data/Repository/AuthDataRepositoryImpl.swift b/DevLog/Data/Repository/AuthDataRepositoryImpl.swift
index e580a044..47eb308d 100644
--- a/DevLog/Data/Repository/AuthDataRepositoryImpl.swift
+++ b/DevLog/Data/Repository/AuthDataRepositoryImpl.swift
@@ -33,7 +33,7 @@ final class AuthDataRepositoryImpl: AuthDataRepository {
     }
     
     func fetchAllProviders() async throws -> [AuthProvider] {
-        let providerStrings = authService.providerIDs ?? []
+        let providerStrings = authService.providerIDs
         return providerStrings.compactMap { AuthProvider(rawValue: $0) }
     }
     
diff --git a/DevLog/Data/Repository/AuthenticationRepositoryImpl.swift b/DevLog/Data/Repository/AuthenticationRepositoryImpl.swift
index 54fc5681..ebb1b651 100644
--- a/DevLog/Data/Repository/AuthenticationRepositoryImpl.swift
+++ b/DevLog/Data/Repository/AuthenticationRepositoryImpl.swift
@@ -63,20 +63,25 @@ final class AuthenticationRepositoryImpl: AuthenticationRepository {
     }
 
     func delete() async throws {
-        guard let uid = authService.uid,
-              let providerID = try await authService.getProviderID(),
-              let provider = AuthProvider(rawValue: providerID)
-        else {
+        guard let uid = authService.uid else {
             throw AuthError.notAuthenticated
         }
 
-        switch provider {
-        case .apple:
-            try await appleAuthService.deleteAuth(uid)
-        case .github:
-            try await githubAuthService.deleteAuth(uid)
-        case .google:
-            try await googleAuthService.deleteAuth(uid)
+        let providers = authService.providerIDs.compactMap { AuthProvider(rawValue: $0) }
+
+        for provider in providers {
+            switch provider {
+            case .apple:
+                try await appleAuthService.deleteAuth(uid)
+            case .github:
+                try await githubAuthService.deleteAuth(uid)
+            case .google:
+                try await googleAuthService.deleteAuth(uid)
+            }
         }
+
+        try await authService.deleteFirestoreUserData()
+        try await authService.deleteCurrentUser()
+        try await authService.clearCurrentSession()
     }
 }
diff --git a/DevLog/Infra/Service/AuthService.swift b/DevLog/Infra/Service/AuthService.swift
index c47e5645..1368e8df 100644
--- a/DevLog/Infra/Service/AuthService.swift
+++ b/DevLog/Infra/Service/AuthService.swift
@@ -7,17 +7,21 @@
 
 import FirebaseAuth
 import FirebaseFirestore
+import FirebaseFunctions
+import FirebaseMessaging
 
 final class AuthService {
     private let store = Firestore.firestore()
+    private let functions = Functions.functions(region: "asia-northeast3")
+    private let messaging = Messaging.messaging()
     private let logger = Logger(category: "AuthService")
 
     var uid: String? {
         Auth.auth().currentUser?.uid
     }
 
-    var providerIDs: [String]? {
-        Auth.auth().currentUser?.providerData.map { $0.providerID }
+    var providerIDs: [String] {
+        Auth.auth().currentUser?.providerData.map { $0.providerID } ?? []
     }
 
     func getProviderID() async throws -> String? {
@@ -42,4 +46,33 @@ final class AuthService {
             throw error
         }
     }
+
+    func deleteFirestoreUserData() async throws {
+        logger.info("Deleting Firestore user data")
+
+        let deleteFunction = functions.httpsCallable("deleteUserFirestoreData")
+        _ = try await deleteFunction.call()
+    }
+
+    func deleteCurrentUser() async throws {
+        logger.info("Deleting FirebaseAuth current user")
+
+        guard let currentUser = Auth.auth().currentUser else {
+            logger.warning("No current user to delete")
+            throw AuthError.notAuthenticated
+        }
+
+        try await currentUser.delete()
+    }
+
+    func clearCurrentSession() async throws {
+        logger.info("Clearing current auth session")
+
+        do {
+            try await messaging.deleteToken()
+        } catch {
+            logger.error("Failed to delete FCM token while clearing session", error: error)
+        }
+        try Auth.auth().signOut()
+    }
 }
diff --git a/DevLog/Infra/Service/SocialLogin/AppleAuthenticationService.swift b/DevLog/Infra/Service/SocialLogin/AppleAuthenticationService.swift
index 635131df..19b9f5cd 100644
--- a/DevLog/Infra/Service/SocialLogin/AppleAuthenticationService.swift
+++ b/DevLog/Infra/Service/SocialLogin/AppleAuthenticationService.swift
@@ -105,14 +105,6 @@ final class AppleAuthenticationService: AuthenticationService {
         let token = try await refreshAppleAccessToken()
 
         try await revokeAppleAccessToken(token: token)
-
-        let deleteFunction = functions.httpsCallable("deleteUserFirestoreData")
-
-        _ = try await deleteFunction.call(["uid": uid])
-
-        try await user?.delete()
-        try await messaging.deleteToken()
-        try Auth.auth().signOut()
     }
 
     func link(uid: String, email: String) async throws {
diff --git a/DevLog/Infra/Service/SocialLogin/GithubAuthenticationService.swift b/DevLog/Infra/Service/SocialLogin/GithubAuthenticationService.swift
index d9aeaa20..77265ac1 100644
--- a/DevLog/Infra/Service/SocialLogin/GithubAuthenticationService.swift
+++ b/DevLog/Infra/Service/SocialLogin/GithubAuthenticationService.swift
@@ -82,14 +82,6 @@ final class GithubAuthenticationService: NSObject, AuthenticationService {
 
     func deleteAuth(_ uid: String) async throws {
         try await revokeAccessToken()
-
-        let deleteFunction = functions.httpsCallable("deleteUserFirestoreData")
-
-        _ = try await deleteFunction.call(["uid": uid])
-
-        try await user?.delete()
-        try await messaging.deleteToken()
-        try Auth.auth().signOut()
     }
 
     func link(uid: String, email: String) async throws {
diff --git a/DevLog/Infra/Service/SocialLogin/GoogleAuthenticationService.swift b/DevLog/Infra/Service/SocialLogin/GoogleAuthenticationService.swift
index 3fb15f44..0d094154 100644
--- a/DevLog/Infra/Service/SocialLogin/GoogleAuthenticationService.swift
+++ b/DevLog/Infra/Service/SocialLogin/GoogleAuthenticationService.swift
@@ -78,15 +78,8 @@ final class GoogleAuthenticationService: AuthenticationService {
     }
 
     func deleteAuth(_ uid: String) async throws {
-        let deleteFunction = functions.httpsCallable("deleteUserFirestoreData")
-
-        _ = try await deleteFunction.call(["uid": uid])
-
-        try await user?.delete()
         GIDSignIn.sharedInstance.signOut()
         try await GIDSignIn.sharedInstance.disconnect()
-        try await messaging.deleteToken()
-        try Auth.auth().signOut()
     }
 
     func link(uid: String, email: String) async throws {
diff --git a/Firebase/functions/src/user/delete.ts b/Firebase/functions/src/user/delete.ts
index 0ca9dfd2..80ee4d98 100644
--- a/Firebase/functions/src/user/delete.ts
+++ b/Firebase/functions/src/user/delete.ts
@@ -1,5 +1,6 @@
 import { onCall, HttpsError } from "firebase-functions/v2/https";
 import * as admin from "firebase-admin";
+import * as logger from "firebase-functions/logger";
 
 export const deleteUserFirestoreData = onCall({
         cors: true,
@@ -7,9 +8,14 @@ export const deleteUserFirestoreData = onCall({
         region: "asia-northeast3"
     },
     async (request) => {
-        if (!request.auth) throw new HttpsError("unauthenticated", "로그인 필요");
-        const uid = request.data.uid;
-        if (!uid) throw new HttpsError("invalid-argument", "uid 필요");
+        if (!request.auth?.uid) {
+            logger.error("deleteUserFirestoreData called without authenticated uid", {
+                auth: request.auth ?? null
+            });
+            throw new HttpsError("unauthenticated", "로그인 필요");
+        }
+
+        const uid = request.auth.uid;
 
         try {
             const userDocRef = admin.firestore().doc(`users/${uid}`);