diff --git a/.changes/fix-custom-signer-uninstaller.md b/.changes/fix-custom-signer-uninstaller.md
new file mode 100644
index 000000000..f3d1e6a16
--- /dev/null
+++ b/.changes/fix-custom-signer-uninstaller.md
@@ -0,0 +1,5 @@
+---
+"tauri-bundler": patch:bug
+---
+
+Fix custom Windows sign command failing to sign app uninstaller if it references relative paths.
\ No newline at end of file
diff --git a/crates/tauri-bundler/src/bundle/windows/sign.rs b/crates/tauri-bundler/src/bundle/windows/sign.rs
index 3c4cd9573..d24b9135b 100644
--- a/crates/tauri-bundler/src/bundle/windows/sign.rs
+++ b/crates/tauri-bundler/src/bundle/windows/sign.rs
@@ -142,12 +142,21 @@ pub fn sign_command_custom<P: AsRef<Path>>(
 ) -> crate::Result<Command> {
   let path = path.as_ref();
 
+  let cwd = std::env::current_dir()?;
+
   let mut cmd = Command::new(&command.cmd);
   for arg in &command.args {
     if arg == "%1" {
       cmd.arg(path);
     } else {
-      cmd.arg(arg);
+      let path = Path::new(arg);
+      // turn relative paths into absolute paths - so the uninstall command can use them
+      // since the !uninstfinalize NSIS hook runs in a different directory
+      if path.exists() && path.is_relative() {
+        cmd.arg(cwd.join(path));
+      } else {
+        cmd.arg(arg);
+      }
     }
   }
   Ok(cmd)