Onion OS is the premier custom firmware for the Miyoo Mini Plus. This guide walks you through every step from a blank MicroSD card to a fully configured retro gaming machine.
What You Need
- Miyoo Mini Plus
- MicroSD card (32GB–256GB, Samsung or SanDisk recommended)
- Windows, Mac, or Linux computer with a card reader
Step 1: Download Onion OS
Visit the Onion OS GitHub releases page and download the latest .zip file.
Step 2: Format Your MicroSD Card
Format as FAT32. On Windows, use the official SD Card Formatter. On macOS, use Disk Utility → Erase → MS-DOS (FAT).
Step 3: Install Onion OS Files
Extract the zip file and copy the contents (not the folder) to the root of your MicroSD card. Your card root should contain folders like App, Emu, RApp, and miyoo.
Step 4: First Boot
Insert the card into your Miyoo Mini Plus and power on. Onion OS will auto-launch an installation wizard. Choose your cores, wait ~2 minutes, and reboot when prompted.
Step 5: Add Your ROMs
Onion OS creates standard ROM folders at the root of your card:
.../Roms/GBA/→ Game Boy Advance.../Roms/SFC/→ Super Nintendo.../Roms/PS/→ PlayStation 1.../Roms/FC/→ NES / Famicom
Copy your legal ROM backups there, launch the Games app, and you're done.
Recommended Settings
- Performance Mode: Enabled (pushes CPU to 1.4GHz)
- Screen Brightness: 7–8 out of 10
- Sleep Timeout: 3 minutes