How to completely clean Xiaomi Redmi 9: from cache to reset to factory settings

Xiaomi Redmi 9 is one of the most popular budget smartphones, but over time even it starts to “brake” due to clogged memory, fragmented files and overloaded cache. If your device becomes slower, applications suddenly close, and memory ends after a couple of photos — it’s time to do a general cleaning. In this guide, we will analyze all the ways of cleaning, from manually cleaning garbage to completely resetting to factory settings, taking into account the features of MIUI firmware and the hardware limitations of Redmi 9.

It's important to understand that cleaning isn't just about removing unnecessary files, it's about optimizing storage, resetting cache of system and user applications, removing duplicates, and in extreme cases, getting your smartphone back to a clean state, and how to do this safely so you don't lose important data, and what tools Xiaomi has in place to do this.

1.Diagnostics: Why does Redmi 9 need cleaning?

Before you start, determine what exactly is slowing down your smartphone. Redmi 9 is equipped with 32/64 GB of memory (depending on the modification) and 3-4 GB of RAM - this is enough for basic tasks, but over time resources are exhausted.

• 📉 Memory is 90 full%+ (checks in the settings → The phone. → Warehouse).
• 🐢 Applications open or fly out with the error “Not enough memory».
• 🔄 Smartphone spontaneously restarts when you start games or cameras.
• 📱 Task Manager has more than 20 background processes (open via Additional) → Task Manager).
• 🔋 The battery sits down in 4-5 hours with moderate use (related to overloading of RAM).

If you know 2-3 of the items on the list, it's a littered system. But don't rush to reset the settings! Try the soft cleaning methods first.

2. Cleaning up cache and debris without data loss

Starting with the safest way to delete temporary files, app cache and system debris can take up to 5-7 GB on Redmi 9, especially if you’re actively using social media, instant messengers and games.

Clearing the cache of individual applications

Some programs (e.g. Facebook, Instagram, Telegram) accumulate gigabytes of cache to delete it:

1. Go to Settings → Applications → Application Management.
2. Select an app (like YouTube) and tap Storage.
3. Click Clear Cache (not to be confused with Clear Data – it will delete accounts!).

Mass cleaning of the cache

To avoid cleaning each application manually:

1. Open the Settings → Storage.
2. Tap Clean in the "Cash" section.
3. Confirm action. This will delete the cache of all applications, but it will not affect personal data.

After cleaning the cache, restart your smartphone, which will help the system recalculate the space available. If memory is still lacking, move on to the next step.

3. Delete unnecessary files and duplicates

Even if you regularly delete photos, Redmi 9 still has invisible files: screenshots, downloads from instant messengers, duplicate contacts and media, and use built-in and third-party tools to find them.

3.1 Built-in Cleanup utility in MIUI

Xiaomi has its own utility for searching for garbage:

1. Launch the Security app (the shield icon).
2. Go to the Cleanup tab.
3. Press Deep Clean – the system will scan the device for:

• 🗑️ Unnecessary APK-Files (remains after application installation).
• 📁 Empty folders.
• 📄 Duplicate photos and documents.
• 🎵 Unused audio files (e.g. ringtones).

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If the Cleanup utility doesn't find garbage, try third-party apps like Files by Google or CCleaner, which scan memory more deeply but require permission to access files.

Manual cleaning of folders

Some files are not visible to the utility. manually check the following folders (use any file manager, such as Mi File Manager):

• 📂 /storage/emulated/0/Download — Here are loads from browsers.
• 📂 /storage/emulated/0/DCIM/.thumbnails — Photo and video miniatures (can be deleted).
• 📂 /storage/emulated/0/Android/data — cache of games and applications (remove folders of unnecessary programs).
• 📂 /storage/emulated/0/MIUI/Backup — backups.

⚠️ Note: Do not delete folders with names com.android, com.xiaomi or system – this can cause a crash MIUI!

4.Storage optimization: file transfer and cloud services

If the memory on Redmi 9 runs out despite being cleaned, consider expanding storage.The device has a microSD slot (up to 512GB), but not all files can be transferred to the card.

4.1. Transfer of applications to a memory card

Not all programs support transfer, but it’s worth trying:

1. Go to Settings → Applications → Application Management.
2. Select an app (like Spotify) and tap Storage.
3. If the option is active, click Change and select Memory Card.

4.2. Use of cloud storage

For photos and documents, it is convenient to use the cloud:

• 🌥️ Google Photos – Automatic upload of photos in original quality (15 GB free).
• 🌥️ Mi Cloud – 5 GB from Xiaomi, integrated with MIUI.
• 🌥️ Yandex Disk or Mail.ru Cloud – 10-20 GB for Russian users.

After transferring files to the cloud or memory card, be sure to clear the basket in the gallery and file managers – otherwise the files will remain in place.

5. Reset to factory settings: when and how to do

If the soft methods didn’t work and the smartphone still slows down, the last resort is Hard Reset, which will delete all data, including apps, photos, contacts and settings, so first:

• 🔄 Make a backup copy through Settings → Additionally. → Backup and reset.
• 📱 Save your contacts to your Google Account or export them to a.vcf file.
• 📷 Transfer the photos to a PC or memory card.

When you're done, reset:

1. Go to Settings → About the phone → Reset settings.
2. Choose Reset all settings.
3. Enter your password (if installed) and confirm.
4. Wait for the reboot (it will take 5-10 minutes).

⚠️ Attention: Redmi 9 with firmware MIUI 12+ You may need to re-link your Mi Account after reset, and if you forget your password, unlocking it will take up to 72 hours!

6. Flash-through: a last resort for power users

If the reset didn’t work (for example, because of a damaged firmware), it remains to reinstall MIUI, a complex procedure that requires a PC and knowledge of fastboot commands.

• 🔧 The smartphone is not turned on or constantly restarted.
• 📱 After the reset, there are still “artifacts” (for example, old applications).
• 🔄 You want to upgrade to a new version. MIUI manually.

For flashing:

1. Download the official firmware for Redmi 9 (codename Lancelot) from Xiaomi’s website.
2. Unpack the archive and copy the folder to the root of the memory card.
3. Press Volume Up + Power to enter Recovery Mode.
4. Select Install update.zip and confirm.

fastboot flash boot boot.img


fastboot flash recovery recovery.img




fastboot flash system system.img




fastboot reboot

⚠️ Warning: The wrong firmware can turn Redmi 9 into a brick. If you're not sure, contact the service center. DRM-The keys will stop working on Widevine. L1 (The quality of streaming on Netflix will decrease).

7.Prevention: How to avoid clogging Redmi 9 in the future

To avoid repeating the cleaning every couple of months, follow the following simple rules:

• 📵 Remove unused apps (especially games – they take up to 2-3 GB each).
• 📷 Regularly transfer photos to the PC or cloud.
• 🔄 Clear the messenger cache (in Telegram: Settings) → Data and memory → Clear the cache).
• 🚫 Turn off autoload media on WhatsApp and Viber.
• 🔋 Use the "Light Mode" in MIUI (Settings → Special opportunities → Easy regime).

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Regularly cleaning the cache and removing duplicate files extends the life of Redmi 9 by 1-2 years without loss of performance.

FAQ: Frequent questions about cleaning Xiaomi Redmi 9