Onion OS is the custom firmware that turns the Miyoo Mini Plus from "good handheld" into "great one." This guide covers what Onion OS is, which devices actually run it, the six benefits you'll feel within the first hour, and what installation involves. Updated for 2026.
Don't own one yet? The Miyoo Mini Plus runs Onion OS better than any other handheld. Get it at LitNXT for $65.99 → (use code NY2026 for 12% off).
What is Onion OS?
Onion OS — often written OnionOS — is an open-source custom firmware built by the community specifically for the Miyoo Mini and Miyoo Mini Plus. It replaces the stock OS on your microSD card; your device's internal firmware stays untouched, so it's completely reversible. Pull the SD card and you're back to stock.
It exists because the stock Miyoo OS, while functional, is missing nearly every modern feature retro gamers expect: save states, rewind, organized game libraries, box-art scraping, themes, and consistent emulator settings. Onion OS adds all of that and more.
Which devices run Onion OS?
Official Onion supports exactly two devices:
- Miyoo Mini (the original)
- Miyoo Mini Plus
One release covers both — there is no separate Mini-only or Plus-only download.
Anything else advertised as "Onion" is a community or vendor adaptation rather than the official build. The common case is the Miyoo Mini Flip, which ships from some sellers with a modified build; that has its own breakdown in Onion OS on the Miyoo Mini Flip. Other handhelds have their own firmware scenes entirely — Anbernic devices run GarlicOS, muOS or stock, and TrimUI devices have their own community builds.
Firmware requirements
Onion needs a recent enough device firmware underneath it:
| Device | Minimum firmware |
|---|---|
| Miyoo Mini | 20220419**** |
| Miyoo Mini Plus | 20230505**** |
Most units produced after July 2022 already qualify, so in practice most people never touch this. If yours is older, note that flashing device firmware — unlike installing Onion — carries a genuine bricking risk.
Why use Onion OS on your Miyoo Mini Plus — 6 reasons
1. Better emulator performance
The first thing you'll notice is how much smoother everything feels. The firmware is tuned to reduce input lag and bump emulator performance across NES, SNES, Game Boy Advance, and PlayStation 1. PS1 in particular goes from "playable" on stock to "fluid" on Onion OS.
If you've ever had Castlevania: Symphony of the Night freeze or Pokémon Emerald crash mid-battle on stock, Onion OS is the fix.
2. Clean, organized UI
The stock OS surfaces every game in one flat menu. Onion OS sorts your library by console, lets you favorite titles, supports themes, and gives you a "recently played" view via GameSwitcher — press MENU and you get a carousel of screenshots from recent sessions, each resuming exactly where you left off. Browsing 500+ ROMs becomes pleasant instead of a chore.
3. Real save states (and rewind)
Onion OS gives you multiple named save states per game, optional auto-save on exit, and rewind support in compatible emulators. This single feature changes how you play — you can experiment with tough boss fights without losing 40 minutes of progress.
4. Box art and metadata
Onion OS supports artwork scraping, so your library shows cover images, console logos, and release info next to each title. The handheld stops feeling like a file browser and starts feeling like a curated shelf.
5. Themes and deep customization
Themes change the background, category entries, console icons, fonts and background music, and they apply globally across every Onion app. There's a large community repository and an on-device Themes app for switching between them — see the best Onion OS themes and how to install them for the tour.
6. Everything else that ships with it
A full RetroArch build tuned for the Mini's screen, standalone emulators like PCSX and ScummVM where they perform better, more than 60 pre-configured game ports, an activity tracker, a screen recorder, a package manager, search that makes a 10,000-ROM card usable, and a guest mode.
What the hardware can actually emulate
Onion doesn't change the silicon, but it does squeeze more out of it than stock does. Realistic expectations:
| System | How it runs |
|---|---|
| NES, SNES, Game Boy / Color / Advance | Full speed, no fuss. The device's core competency. |
| Sega Master System, Genesis, Game Gear | Full speed. |
| PlayStation 1 | Very good with the right BIOS and per-game settings; the heaviest 3D titles need tweaking. |
| Neo Geo, CPS1/2 | Mostly fine, arcade dependent. |
| Nintendo 64, Dreamcast, PSP | Not realistically. This is not the device for it. |
If your library is 8-bit and 16-bit with some PS1, a Mini Plus running Onion is close to ideal. If you want GameCube or PSP, you're shopping in a different price bracket — see our best handhelds for GameCube emulation guide.
How to install Onion OS: the short version
Installation takes about 15 minutes and only writes to the microSD card, so it's fully reversible.
- Check your device firmware meets the minimum above.
- Format the card as FAT32 (not exFAT or NTFS).
- Copy the Onion release files to the root of the card — or let Onion Desktop Tools do it for you on Windows.
- Insert the card, power on, and let the on-device installer run.
Full walkthrough with both methods, first-boot setup and troubleshooting: How to install Onion OS on the Miyoo Mini Plus.
How Onion compares to other custom firmware
GarlicOS — the Anbernic RG35XX equivalent. Similar philosophy, different hardware; our Miyoo Mini Plus vs Anbernic RG35XX comparison covers both sides.
MinUI — deliberately minimal. No box art, no themes, no activity tracking; just a fast list of games and instant resume. Some people prefer it precisely because Onion does so much.
muOS — the newer Anbernic-focused option, actively developed and more configurable than GarlicOS.
Allium — built for newer Miyoo hardware, and the usual recommendation on the Miyoo Mini Flip where official Onion doesn't reach.
Onion's advantage is polish and breadth on the device it targets. Its disadvantage is that it targets only that device, and its release cadence has slowed — the community increasingly treats the v4.3 line as a stable end point. That's not a reason to avoid it, but don't buy expecting a stream of new features.
Want box art on every game?
Once Onion OS is installed, the next upgrade is automatic box art. We have a complete guide for that: How to Add Box Art to OnionOS / GarlicOS.
Other handhelds worth a look
Onion OS is Miyoo-specific, but if you're shopping around, these are the handhelds we recommend alongside the Mini Plus:
| Device | Why | Price | Buy |
|---|---|---|---|
| Miyoo Mini Plus | Best Onion OS device. The reference. | $65.99 | LitNXT → |
| Miyoo Mini V4 | Smaller form factor, officially supported by Onion | $109.99 | LitNXT → |
| Miyoo Mini Flip | Clamshell; ships with a community Onion build | $75.99 | LitNXT → |
| Miyoo Flip V2 | Newer clamshell, Surwish OS variant | $89.99 | LitNXT → |
Browse our full Miyoo device guide to compare every model side-by-side.
Frequently asked questions
Does the Miyoo Mini Plus come with Onion OS installed? Not from Miyoo. Some resellers pre-load it onto the bundled SD card, which is why two seemingly identical listings can behave completely differently out of the box.
Will installing Onion brick my device? Installing Onion only writes to the SD card, so it's low risk and fully reversible. The risky operation is upgrading the device firmware, which is a separate step most people never need.
Do I lose my saves when updating? No, as long as you're upgrading rather than reformatting. Saves and save states live in their own folders on the card.
Bottom line
If you own a Miyoo Mini Plus and you're still on stock firmware, you're using maybe 40% of what the device can do. Onion OS is free, takes 15 minutes to install, doesn't risk your hardware, and is reversible. There's almost no reason not to.
Need to grab a Miyoo Mini Plus first? Buy it at LitNXT for $65.99 → — use NY2026 at checkout for 12% off.
