diff --git a/nx/include/switch/services/hiddbg.h b/nx/include/switch/services/hiddbg.h
index df4aaf3d..c5c6c5b7 100644
--- a/nx/include/switch/services/hiddbg.h
+++ b/nx/include/switch/services/hiddbg.h
@@ -137,6 +137,12 @@ Result hiddbgAcquireOperationEventHandle(Event* out_event, bool autoclear, u64 U
 /// Only available with [6.0.0+].
 Result hiddbgReadSerialFlash(u32 offset, void* buffer, size_t size, u64 UniquePadId);
 
+/// Writes spi-flash for the specified controller. See hidsys.h for UniquePadId.
+/// buffer and tmem_size must be page-aligned. size is the actual transfer size.
+/// This also uses \ref hiddbgAcquireOperationEventHandle to wait for the operation to finish, then \ref hiddbgGetOperationResult is used.
+/// Only available with [6.0.0+].
+Result hiddbgWriteSerialFlash(u32 offset, void* buffer, size_t tmem_size, size_t size, u64 UniquePadId);
+
 /// Get the Result for the Operation and handles cleanup, for the specified controller. See hidsys.h for UniquePadId.
 /// Only available with [6.0.0+].
 Result hiddbgGetOperationResult(u64 UniquePadId);
diff --git a/nx/source/services/hiddbg.c b/nx/source/services/hiddbg.c
index f4372cae..7165b99c 100644
--- a/nx/source/services/hiddbg.c
+++ b/nx/source/services/hiddbg.c
@@ -130,7 +130,21 @@ static Result _hiddbgReadSerialFlash(TransferMemory *tmem, u32 offset, u64 size,
     );
 }
 
-// sdk-nso doesn't use hiddbgAcquireOperationEventHandle/hiddbgGetOperationResult in the ReadSerialFlash impl, those are used seperately by the user.
+static Result _hiddbgWriteSerialFlash(TransferMemory *tmem, u32 offset, u64 tmem_size, u64 size, u64 UniquePadId) {
+    const struct {
+        u32 offset;
+        u64 tmem_size;
+        u64 size;
+        u64 UniquePadId;
+    } in = { offset, tmem_size, size, UniquePadId };
+
+    return serviceDispatchIn(&g_hiddbgSrv, 230, in,
+        .in_num_handles = 1,
+        .in_handles = { tmem->handle },
+    );
+}
+
+// sdk-nso doesn't use hiddbgAcquireOperationEventHandle/hiddbgGetOperationResult in the *SerialFlash impl, those are used seperately by the user. [9.0.0+] sdk-nso no longer exposes *SerialFlash and related functionality.
 Result hiddbgReadSerialFlash(u32 offset, void* buffer, size_t size, u64 UniquePadId) {
     Result rc=0;
     Event tmpevent={0};
@@ -153,6 +167,26 @@ Result hiddbgReadSerialFlash(u32 offset, void* buffer, size_t size, u64 UniquePa
     return rc;
 }
 
+Result hiddbgWriteSerialFlash(u32 offset, void* buffer, size_t tmem_size, size_t size, u64 UniquePadId) {
+    Result rc=0;
+    Event tmpevent={0};
+    TransferMemory tmem;
+
+    if (hosversionBefore(6,0,0))
+        return MAKERESULT(Module_Libnx, LibnxError_IncompatSysVer);
+
+    rc = tmemCreateFromMemory(&tmem, buffer, tmem_size, Perm_R);
+    if (R_FAILED(rc)) return rc;
+
+    rc = hiddbgAcquireOperationEventHandle(&tmpevent, true, UniquePadId); // *Must* be used before _hiddbgWriteSerialFlash.
+    if (R_SUCCEEDED(rc)) rc = _hiddbgWriteSerialFlash(&tmem, offset, tmem_size, size, UniquePadId);
+    if (R_SUCCEEDED(rc)) rc = eventWait(&tmpevent, U64_MAX);
+    if (R_SUCCEEDED(rc)) rc = hiddbgGetOperationResult(UniquePadId);
+    eventClose(&tmpevent);
+    tmemClose(&tmem);
+    return rc;
+}
+
 Result hiddbgGetOperationResult(u64 UniquePadId) {
     if (hosversionBefore(6,0,0))
         return MAKERESULT(Module_Libnx, LibnxError_IncompatSysVer);