How to install OnionOS on Miyoo Mini Plus (2025)

OnionOS is the most popular custom firmware for the Miyoo Mini Plus. The install process takes about 15 minutes and doesn’t require any technical knowledge — just a computer and an SD card.

Before you start

What you’ll need:

• Miyoo Mini Plus (also works with Miyoo Flip)
• MicroSD card — 32GB minimum, 64-128GB recommended. Use a quality brand (Samsung, SanDisk)
• SD card reader for your computer
• Computer (Windows, Mac, or Linux)
• Game ROMs — legally obtained from cartridges you own

Time required: ~15 minutes

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Step 1: Format your SD card

OnionOS requires a freshly formatted SD card. Do not skip this step — an improperly formatted card is the #1 cause of installation issues.

Windows:

1. Download SD Card Formatter from the SD Association
2. Insert your SD card
3. Open SD Card Formatter
4. Select your card drive
5. Choose “Overwrite format”
6. Format as FAT32 (cards 32GB or smaller) or exFAT (cards larger than 32GB)

macOS:

1. Open Disk Utility
2. Select your SD card from the left sidebar
3. Click Erase
4. Format: MS-DOS (FAT) for 32GB, ExFAT for larger
5. Click Erase

Linux:

# Replace /dev/sdX with your SD card device
sudo mkfs.fat -F 32 /dev/sdX1  # for 32GB or smaller
sudo mkfs.exfat /dev/sdX1      # for larger than 32GB

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Step 2: Download OnionOS

1. Go to the official OnionOS GitHub releases page
2. Download the latest release — look for the file named Onion-v4.x.x.zip (the version number will vary)
3. Do NOT download from any other source. Only use the official GitHub repository

⚠️ Important: Never download OnionOS from random websites, YouTube links, or file-sharing services. The official GitHub is the only trusted source.

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Step 3: Extract and copy to SD card

1. Extract the downloaded ZIP file on your computer
2. You’ll see a folder structure that looks like this:

   BIOS/
   Emu/
   App/
   miyoo/
   RetroArch/
   Saves/
   .tmp_update/

3. Copy everything from the extracted folder to the root of your SD card
4. Make sure the files are at the root level — not inside a subfolder

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Step 4: First boot (installation)

1. Safely eject the SD card from your computer
2. Insert it into your Miyoo Mini Plus
3. Turn on the device
4. OnionOS will begin its automatic installation — you’ll see a progress screen
5. The device will reboot itself when done (this may happen 2-3 times)
6. Do not turn off the device during installation!

The first boot takes about 2-3 minutes. Be patient.

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Step 5: Initial setup

After installation completes, OnionOS will walk you through initial setup:

1. Language — select your preferred language
2. Time zone — set your local time zone
3. Theme — choose a UI theme (you can change this later)
4. Wi-Fi (optional) — connect to your network for artwork scraping and RetroAchievements

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Step 6: Add your games (ROMs)

1. Turn off the Miyoo Mini Plus
2. Remove the SD card and insert it in your computer
3. Copy your ROM files to the appropriate folders:

Platform	Folder	Accepted Formats
Game Boy	Roms/GB/	.gb, .gbc, .zip
Game Boy Advance	Roms/GBA/	.gba, .zip
NES	Roms/FC/	.nes, .zip
SNES	Roms/SFC/	.sfc, .smc, .zip
PlayStation 1	Roms/PS/	.bin/.cue, .pbp, .chd
Sega Genesis	Roms/MD/	.md, .gen, .zip

4. Safely eject and reinsert the SD card into the device
5. Turn on — OnionOS will scan for new games automatically

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Step 7: Add BIOS files (required for some systems)

Some emulators require BIOS files to run. The most common:

System	BIOS File	Required?
PS1	scph1001.bin	✅ Yes
GBA	gba_bios.bin	Recommended
NDS	bios7.bin, bios9.bin, firmware.bin	✅ Yes

Copy BIOS files to the BIOS/ folder on your SD card.

We can’t provide BIOS files — you’ll need to dump them from your own consoles or find them through your own means.

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Troubleshooting

Device won’t boot after installation

• Remove the SD card and reformat it using Step 1
• Re-download OnionOS and try again
• Try a different SD card — cheap/counterfeit cards are a common issue

Games aren’t showing up

• Make sure ROMs are in the correct folders (see Step 6)
• Go to Apps → Refresh ROMs in the OnionOS menu
• Check that your ROM format is supported

Screen is black after boot

• Hold the power button for 10 seconds to force restart
• If it persists, the SD card may be faulty

Wi-Fi won’t connect

• OnionOS only supports 2.4GHz networks (not 5GHz)
• Make sure your Wi-Fi password is entered correctly
• Try moving closer to your router

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What to do next

Now that OnionOS is running, some things worth exploring:

• RetroAchievements — earn achievements in classic games. Set up in Settings → RetroArch → Achievements
• Themes — browse community themes in Apps → Theme Store
• Artwork scraping — connect to Wi-Fi and use the built-in scraper for box art
• Save states — RetroArch’s quick save/load is a game changer for hard games

Related:

• What is OnionOS? — more on features
• Best retro handhelds under $100 — other device options
• OnionOS firmware tracker — latest updates