In this tutorial, we will guide you to install Android 12 Custom ROM on Xiaomi Mi 9 (codenamed cepheus). Talking about Xiaomi Mi 9, the phone sports a...
Abd Razaaq
Last updated on February 16, 2026
Abd Razaaq
Author
I'm a Tech Content Writer and Full-Time blogger. Since I love Android and Google's device, I started my career in writing for Android OS and their features. This led me to start "GetDroidTips". I have completed Master of Business Administration at Mangalore University, Karnataka.
In this tutorial, we will guide you to install Android 12 Custom ROM on Xiaomi Mi 9 (codenamed cepheus). Talking about Xiaomi Mi 9, the phone sports a Snapdragon 855 octa-core SoC on-board paired with Adreno 640 GPU, up to 8GB of RAM, and 256GB of UFS 2.1 internal storage. The phone runs on Android 9.0 Pie out-of-the-box and has already received Android 10 and Android 11.
If you are someone who wants to install the vanilla version of Android 12, then this guide is for you.
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Android 12 is all about improved personalization and revamped user interface that changes the way to bring more dynamic expression and a whole new design element. It’s a successor of the last-gen Android 11 which was basically focused on the privacy and security of the user data. While the Android 12 not only focused on privacy features but also on visual treatment.
Talking about the features, it has all new and colorful yet minimal widgets that are now more dynamic than ever before. While the dynamic theme with the wallpapers is more expressive as per your mood. The notification shade, lock screen, and its notifications, glance screen, volume controls, quick shortcut tiles, new power menu, transitions or animations, etc everything looks & feels great whatsoever with ‘Material You’ design.
Meanwhile, the impressive Privacy Dashboard feature, the privacy indicator on the top of the screen is also great. Whereas scrolling screenshot support, improved notifications, and quick reply feature, on-device search feature, easy Wi-Fi sharing, one-handed mode, quick back tap feature, haptic-coupled audio effect, Android 12 updates via Google Play, App hibernation, all-new emojis, improved auto-rotate, and a lot more.
WHAT WORKS? Almost everything SELinux is enforcing WiFi Audio RIL GPS Camera Flashlight NFC Fingerprint on display Vibration Bluetooth FM Radio Cast Any other thing that is not listed in the "What doesn't work" list WHAT DOESN'T WORK? You tell me
As the title suggests, here we’ve shared the requirements and steps to flash the AOSP Android 12 build on the Xiaomi Mi 9 (cepheus) variant.
Before heading over to the guide, make sure to follow all the requirements below.
Before we begin with this procedure, I would strongly recommend you create a backup of your device storage and all your files stored on your device. Moreover, it is advised to follow the steps mentioned in this post very carefully to avoid permanent damage or to brick your device.
It’s highly recommended to charge your handset before unlocking the bootloader to avoid your device from shutting down occasionally while going through the process. Make sure to keep at least 50% of charge or higher for a smooth operation.
You can skip this adb and fastboot part if you have already installed TWRP Recovery on your Xiaomi Mi 9.
Using the ADB and Fastboot command (platform-tools), you’ll be able to boot your Android device into the bootloader mode (download mode) which will be easy for you to proceed with further steps. ADB (Android Debug Bridge) creates a connection or bridge between the device and computer to sideload files.
Whereas Fastboot is a more advanced command utility tool for Android devices that works with computers. You can download ADB and Fastboot Binaries (Platform-Tools).
A USB Driver is a set of files that basically allows you to create a successful and strong connection between a mobile device with a computer properly using a USB data cable. It’ll be useful to transfer files between the connected devices, flash files on the handset, and more.
It’s also worth mentioning that not only mobile devices but also other external devices can use and run USB Drivers on a Windows computer. Such as mouse, keyboard, printer, external hard drives, speakers, USB flash drives, etc. You can grab Xiaomi USB Drivers here.
To enjoy any custom ROM, you must first unlock the bootloader on your Xiaomi Mi 9.
You have to install TWRP Recovery on your phone to install any custom ROM on your device. After unlocking the bootloader, you can follow our guide to install TWRP Recovery on your Xiaomi Mi 9.
Here, you will find all the Android 12 custom ROM for your Xiaomi Mi 9 (cepheus).
| crDroid v8.1 | XDA Development Page |
| Octavi-OS | XDA Development Page |
| Project Elixir | XDA Development Page |
| EVOLUTION-X Snow 6.0 | XDA Development Page |
| ArrowOS 12.0 | XDA Development Page |
| Lineage OS 19 | XDA Development Page |
It’s worth mentioning that most of the third-party AOSP (Android Open Source Project) ROMs (also known as aftermarket firmware) come without any preinstalled Google apps package. You can manually install the Android 12 GApps by following our guide.
Warning!
GetDroidTips won’t be responsible for any kind of issue that may happen to your device if you flash it on another device and brick it. Do it at your own risk.
adb reboot recovery
TWRP Home
Your device will now boot to the newly installed OS. With this, we conclude the guide on how to install the AOSP Android 12 on Xiaomi Mi 9. Do keep in mind that the first boot might take up some time and you might have to set up your device from scratch.
Flashing the ported Android 12 on your Xiaomi Mi 9 will give an early taste of the latest Android OS version. It looks like that the Xiaomi Mi 9 model won’t gonna receive the Android 12 update officially from the manufacturer. So, it’s a good idea to get most of the features and visual treatment. However, if you find any extra bugs or stability issues then you should report them to the respective forum.
That’s it, guys. We assume this guide was helpful to you. For further queries, you can comment below.
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