If that works, you can make it permanent by editing FileZilla's .desktop shortcut. Copy the system shortcut to your local applications and modify the Exec line.
Historically, FileZilla did not support a native dark mode on Windows. Users had to rely on hacky manifests or system-wide overrides. However, with the release of and the standard FileZilla Client 3.66+ , the developers have slowly introduced partial theming support. filezilla dark theme upd
As of (latest stable as of early 2026), there is still no native, built-in dark theme on Windows and Linux. macOS version inherits the system-wide dark mode (since FileZilla 3.46+), but Windows/Linux users have been waiting for years. If that works, you can make it permanent