diff --git a/dll/win32/shell32/wine/shellpath.c b/dll/win32/shell32/wine/shellpath.c
index e55b48b1c33..4ab83c1f317 100644
--- a/dll/win32/shell32/wine/shellpath.c
+++ b/dll/win32/shell32/wine/shellpath.c
@@ -665,6 +665,184 @@ static BOOL PathMakeUniqueNameA(
 /*************************************************************************
  * PathMakeUniqueNameW	[internal]
  */
+#ifdef __REACTOS__
+/* https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/nf-shlobj_core-pathmakeuniquename */
+static BOOL PathMakeUniqueNameW(
+    _Out_ PWSTR pszUniqueName,
+    _In_ UINT cchMax,
+    _In_ PCWSTR pszTemplate,
+    _In_opt_ PCWSTR pszLongPlate,
+    _In_opt_ PCWSTR pszDir)
+{
+    TRACE("%p %u %s %s %s\n",
+          pszUniqueName, cchMax, debugstr_w(pszTemplate),
+          debugstr_w(pszLongPlate), debugstr_w(pszDir));
+
+    if (!cchMax || !pszUniqueName)
+        return FALSE;
+
+    pszUniqueName[0] = UNICODE_NULL;
+
+    LPWSTR pszDest = pszUniqueName;
+    UINT dirLength = 0;
+    if (pszDir)
+    {
+        if (StringCchCopyW(pszUniqueName, cchMax - 1, pszDir) != S_OK)
+            return FALSE;
+
+        pszDest = PathAddBackslashW(pszUniqueName);
+        if (!pszDest)
+            return FALSE;
+
+        dirLength = lstrlenW(pszDir);
+    }
+
+    PCWSTR pszTitle = pszLongPlate ? pszLongPlate : pszTemplate;
+
+    if (   !pszTitle
+        || !IsLFNDriveW(pszDir)
+#if (NTDDI_VERSION < NTDDI_VISTA)
+        || pszDir
+#endif
+    )
+    {
+        if (!pszTemplate)
+            return FALSE;
+
+        PCWSTR pszSrc = pszTemplate;
+        PCWSTR pchDotExt = PathFindExtensionW(pszTemplate);
+        INT extLength = lstrlenW(pchDotExt);
+
+        WCHAR formatString[MAX_PATH];
+        if (StringCchCopyW(formatString, _countof(formatString), L"%d") != S_OK)
+            return FALSE;
+
+        INT cchTitle = pchDotExt - pszTemplate;
+        if (cchTitle > 1)
+        {
+            PCWSTR pch = pchDotExt - 1;
+            while (cchTitle > 1 && (L'0' <= *pch && *pch <= L'9'))
+            {
+                --cchTitle;
+                --pch;
+            }
+        }
+
+        if (cchTitle > 7)
+            cchTitle = 7;
+
+        while (extLength + cchTitle + dirLength + 1 > (cchMax - 1) && cchTitle > 1)
+            --cchTitle;
+
+        INT maxCount;
+        if (cchTitle >= 1)
+            maxCount = (cchTitle != 1) ? 100 : 10;
+        else
+            maxCount = 1;
+
+        if (StringCchCopyNW(pszDest, cchMax - dirLength, pszSrc, cchTitle) != S_OK)
+            return FALSE;
+
+        LPWSTR pchTitle = pszDest + cchTitle;
+        INT ich;
+        for (ich = 1; ich < maxCount; ++ich)
+        {
+            WCHAR tempName[MAX_PATH];
+            if (StringCchPrintfW(tempName, _countof(tempName), formatString, ich) != S_OK ||
+                StringCchCatW(tempName, _countof(tempName), pchDotExt) != S_OK)
+            {
+                return FALSE;
+            }
+
+            if (StringCchCopyW(pchTitle, cchMax - (pchTitle - pszUniqueName), tempName) != S_OK)
+                return FALSE;
+
+            if (!PathFileExistsW(pszUniqueName))
+                return TRUE;
+        }
+    }
+    else
+    {
+        PCWSTR openParen = StrChrW(pszTitle, L'(');
+        PCWSTR pchDotExt = NULL;
+        INT cchTitle = 0;
+        WCHAR formatString[MAX_PATH];
+
+        if (openParen)
+        {
+            while (openParen)
+            {
+                PCWSTR pch = openParen + 1;
+                while (*pch >= L'0' && *pch <= L'9')
+                    ++pch;
+
+                if (*pch == L')')
+                    break;
+
+                openParen = StrChrW(openParen + 1, L'(');
+            }
+
+            if (openParen)
+            {
+                pchDotExt = openParen + 1;
+                cchTitle = pchDotExt - pszTitle;
+                if (StringCchCopyW(formatString, _countof(formatString), L"%d") != S_OK)
+                    return FALSE;
+            }
+            else
+            {
+                pchDotExt = PathFindExtensionW(pszTitle);
+                cchTitle = pchDotExt - pszTitle;
+                if (StringCchCopyW(formatString, _countof(formatString), L" (%d)") != S_OK)
+                    return FALSE;
+            }
+        }
+        else
+        {
+            pchDotExt = PathFindExtensionW(pszTitle);
+            cchTitle = pchDotExt - pszTitle;
+            if (StringCchCopyW(formatString, _countof(formatString), L" (%d)") != S_OK)
+                return FALSE;
+        }
+
+        INT maxCount = 1;
+        INT remainingChars = cchMax - cchTitle - dirLength - lstrlenW(formatString) + 2;
+
+        if (remainingChars == 1)
+            maxCount = 10;
+        else if (remainingChars == 2)
+            maxCount = 100;
+        else if (remainingChars > 0)
+            maxCount = 1000;
+        else
+            maxCount = 1;
+
+        if (StringCchCopyNW(pszDest, cchMax - dirLength, pszTitle, cchTitle) != S_OK)
+            return FALSE;
+
+        LPWSTR pchTitle = pszDest + cchTitle;
+        INT ich;
+        for (ich = 1; ich < maxCount; ++ich)
+        {
+            WCHAR tempName[MAX_PATH];
+            if (StringCchPrintfW(tempName, _countof(tempName), formatString, ich) != S_OK ||
+                StringCchCatW(tempName, _countof(tempName), pchDotExt) != S_OK)
+            {
+                return FALSE;
+            }
+
+            if (StringCchCopyW(pchTitle, cchMax - (pchTitle - pszUniqueName), tempName) != S_OK)
+                return FALSE;
+
+            if (!PathFileExistsW(pszUniqueName))
+                return TRUE;
+        }
+    }
+
+    pszUniqueName[0] = UNICODE_NULL;
+    return FALSE;
+}
+#else
 static BOOL PathMakeUniqueNameW(
 	LPWSTR lpszBuffer,
 	DWORD dwBuffSize,
@@ -677,6 +855,7 @@ static BOOL PathMakeUniqueNameW(
 	 debugstr_w(lpszLongName), debugstr_w(lpszPathName));
 	return TRUE;
 }
+#endif
 
 /*************************************************************************
  * PathMakeUniqueName	[SHELL32.47]
diff --git a/modules/rostests/apitests/shell32/CMakeLists.txt b/modules/rostests/apitests/shell32/CMakeLists.txt
index 5389915fd87..491a7e65017 100644
--- a/modules/rostests/apitests/shell32/CMakeLists.txt
+++ b/modules/rostests/apitests/shell32/CMakeLists.txt
@@ -24,6 +24,7 @@ list(APPEND SOURCE
     OpenAs_RunDLL.cpp
     PathIsEqualOrSubFolder.cpp
     PathIsTemporary.cpp
+    PathMakeUniqueName.cpp
     PathResolve.cpp
     RealShellExecuteEx.cpp
     SHAppBarMessage.cpp
diff --git a/modules/rostests/apitests/shell32/PathMakeUniqueName.cpp b/modules/rostests/apitests/shell32/PathMakeUniqueName.cpp
new file mode 100644
index 00000000000..abd0c7bed11
--- /dev/null
+++ b/modules/rostests/apitests/shell32/PathMakeUniqueName.cpp
@@ -0,0 +1,119 @@
+/*
+ * PROJECT:     ReactOS api tests
+ * LICENSE:     LGPL-2.1-or-later (https://spdx.org/licenses/LGPL-2.1-or-later)
+ * PURPOSE:     Tests for PathMakeUniqueName
+ * COPYRIGHT:   Copyright 2025 Katayama Hirofumi MZ (katayama.hirofumi.mz@gmail.com)
+ */
+
+#include "shelltest.h"
+#include <stdio.h>
+#include <versionhelpers.h>
+
+#define ok_wstri(x, y) \
+    ok(_wcsicmp(x, y) == 0, "Wrong string. Expected '%S', got '%S'\n", y, x)
+
+/* IsLFNDriveW */
+typedef BOOL (WINAPI *FN_IsLFNDriveW)(LPCWSTR);
+
+START_TEST(PathMakeUniqueName)
+{
+    WCHAR szPath[MAX_PATH], szCurDir[MAX_PATH], szTempDir[MAX_PATH];
+    BOOL result, bUseLong = FALSE;
+    FN_IsLFNDriveW pIsLFNDriveW =
+        (FN_IsLFNDriveW)GetProcAddress(GetModuleHandleW(L"shell32"), MAKEINTRESOURCEA(42));
+
+    // Move to temporary folder
+    GetCurrentDirectoryW(_countof(szCurDir), szCurDir);
+    GetEnvironmentVariableW(L"TEMP", szTempDir, _countof(szTempDir));
+    SetCurrentDirectoryW(szTempDir);
+
+    if (pIsLFNDriveW)
+        bUseLong = pIsLFNDriveW(szTempDir) && IsWindowsVistaOrGreater();
+    trace("bUseLong: %d\n", bUseLong);
+
+    DeleteFileW(L"test.txt");
+
+    // Test 1: Basic operation
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.txt", NULL, NULL);
+    ok_int(result, TRUE);
+    ok_wstri(szPath, L"test (1).txt");
+
+    // Test 2: Specify directory
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.txt", NULL, L".");
+    ok_int(result, TRUE);
+    ok_wstri(szPath, (bUseLong ? L".\\test (1).txt" : L".\\test1.txt"));
+
+    // Test 3: Duplicated filename
+    CreateFileW(L"test.txt", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.txt", NULL, NULL);
+    ok_int(result, TRUE);
+    ok_wstri(szPath, L"test (1).txt");
+    DeleteFileW(L"test.txt");
+
+    // Build long name
+    WCHAR longName[MAX_PATH + 32];
+    for (auto& ch : longName)
+        ch = L'A';
+    longName[_countof(longName) - 10] = UNICODE_NULL;
+    lstrcatW(longName, L".txt");
+
+    // Test 4: Long filename
+    result = PathMakeUniqueName(szPath, _countof(szPath), longName, NULL, NULL);
+    szPath[0] = UNICODE_NULL;
+    ok_int(result, FALSE);
+    ok_wstri(szPath, L"");
+
+    // Test 5: Invalid parameter
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(NULL, 0, L"test.txt", NULL, NULL);
+    ok_int(result, FALSE);
+
+    // Test 6: Template and longplate
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"template.txt", L"longplate.txt", NULL);
+    ok_int(result, TRUE);
+    ok_wstri(szPath, L"longplate (1).txt");
+
+    // Test 7: Template only
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"template.txt", NULL, NULL);
+    ok_int(result, TRUE);
+    ok_wstri(szPath, L"template (1).txt");
+
+    // Test 8: Folder and duplicated filename
+    CreateFileW(L".\\temp\\test.txt", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.txt", NULL, L".");
+    ok_int(result, TRUE);
+    ok_wstri(szPath, (bUseLong ? L".\\test (1).txt" : L".\\test1.txt"));
+    DeleteFileW(L".\\test.txt");
+
+    // Test 9: Test extension
+    CreateFileW(L".\\test.hoge", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.hoge", NULL, L".");
+    ok_int(result, TRUE);
+    ok_wstri(szPath, (bUseLong ? L".\\test (1).hoge" : L".\\test1.hoge"));
+    DeleteFileW(L".\\test.hoge");
+
+    // Test 10: Folder in folder
+    CreateDirectoryW(L".\\hoge", NULL);
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.txt", NULL, L".\\hoge");
+    ok_int(result, TRUE);
+    ok_wstri(szPath, (bUseLong ? L".\\hoge\\test (1).txt" : L".\\hoge\\test1.txt"));
+    RemoveDirectoryW(L".\\hoge");
+
+    // Test 11: File in folder
+    CreateFileW(L".\\hoge.txt", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+    szPath[0] = UNICODE_NULL;
+    result = PathMakeUniqueName(szPath, _countof(szPath), L"test.txt", NULL, L".");
+    ok_int(result, TRUE);
+    ok_wstri(szPath, (bUseLong ? L".\\test (1).txt" : L".\\test1.txt"));
+    DeleteFileW(L".\\hoge.txt");
+
+    SetCurrentDirectoryW(szCurDir);
+}
diff --git a/modules/rostests/apitests/shell32/testlist.c b/modules/rostests/apitests/shell32/testlist.c
index cc5398ddb68..f76eb744a5e 100644
--- a/modules/rostests/apitests/shell32/testlist.c
+++ b/modules/rostests/apitests/shell32/testlist.c
@@ -26,6 +26,7 @@ extern void func_menu(void);
 extern void func_OpenAs_RunDLL(void);
 extern void func_PathIsEqualOrSubFolder(void);
 extern void func_PathIsTemporary(void);
+extern void func_PathMakeUniqueName(void);
 extern void func_PathResolve(void);
 extern void func_PIDL(void);
 extern void func_RealShellExecuteEx(void);
@@ -82,6 +83,7 @@ const struct test winetest_testlist[] =
     { "OpenAs_RunDLL", func_OpenAs_RunDLL },
     { "PathIsEqualOrSubFolder", func_PathIsEqualOrSubFolder },
     { "PathIsTemporary", func_PathIsTemporary },
+    { "PathMakeUniqueName", func_PathMakeUniqueName },
     { "PathResolve", func_PathResolve },
     { "PIDL", func_PIDL },
     { "RealShellExecuteEx", func_RealShellExecuteEx },
diff --git a/sdk/include/psdk/shlobj.h b/sdk/include/psdk/shlobj.h
index 10e73f0ddcd..530b9c07f9b 100644
--- a/sdk/include/psdk/shlobj.h
+++ b/sdk/include/psdk/shlobj.h
@@ -409,6 +409,14 @@ SHStartNetConnectionDialogW(
     _In_ LPCWSTR pszRemoteName,
     _In_ DWORD dwType);
 
+BOOL WINAPI
+PathMakeUniqueName(
+    _Out_ PWSTR pszUniqueName,
+    _In_ UINT cchMax,
+    _In_ PCWSTR pszTemplate,
+    _In_opt_ PCWSTR pszLongPlate,
+    _In_opt_ PCWSTR pszDir);
+
 /*****************************************************************************
  * IContextMenu interface
  */