Samsung Rolls Out One UI 7 Update for Galaxy S21 Series: Features, Build Numbers, and Availability

Samsung is continuing its commitment to deliver timely software updates, and the latest series to receive the highly anticipated One UI 7 update based on Android 15 is the Samsung Galaxy S21 lineup. After several premium Galaxy S series smartphones received the update, Samsung has now started the One UI 7 rollout for Galaxy S21, Galaxy S21 Plus, and Galaxy S21 Ultra.

This marks a significant milestone for the Galaxy S21 series, as One UI 7 based on Android 15 is the final major Android OS update these devices will receive. The smartphones originally launched with Android 11 and have now completed their update journey, receiving four consecutive Android OS versions—a feat that reflects Samsung’s updated software policy for flagship devices.

Let’s explore everything you need to know about the Galaxy S21 One UI 7 update, including new features, build numbers, region availability, and update instructions.

📱 One UI 7 Update Arrives for Galaxy S21 Series

✅ Eligible Devices & Build Numbers

Samsung has begun the initial rollout of One UI 7 (Android 15) for the following Galaxy S21 models in South Korea:

• Samsung Galaxy S21 (SM-G991N) – Build Number: G991NKSU8HYD9

• Samsung Galaxy S21 Plus (SM-G996N) – Build Number: G996NKSU8HYD9

• Samsung Galaxy S21 Ultra (SM-G998N) – Build Number: G998NKSU8HYD9

Each of these updates comes with a hefty 3.5GB update package, so users are advised to connect to a Wi-Fi network before downloading.

🌐 Regional Availability

The initial release is currently exclusive to South Korea, but Samsung is expected to expand the update to global markets, including Europe, India, and the US, in the coming weeks.

Samsung typically rolls out updates in phases, so even within the same region, it might take a few hours or days for all eligible devices to receive the update notification.

🔚 End of Android OS Update Cycle for Galaxy S21

With the release of One UI 7 (Android 15), Samsung has officially delivered four major Android updates to the Galaxy S21 series:

1. Android 11 (Out of the Box)

2. Android 12 (One UI 4)

3. Android 13 (One UI 5)

4. Android 14 (One UI 6)

5. Android 15 (One UI 7) – Final Major Update

Unfortunately, Android 16 will not be coming to the Galaxy S21 series. However, users don’t need to worry about security, as Samsung has promised to continue rolling out regular security patches for these devices for at least another year or two.

✨ What’s New in One UI 7 for Galaxy S21?

Samsung’s One UI 7 is built on Android 15, offering both visual and functional enhancements designed to improve the user experience, performance, and device security. Below is a breakdown of the key features and changes included in the update:

1. 🧭 Vertical Scrolling App Drawer

The horizontal swiping in the app drawer is replaced with a vertical scroll layout, allowing for faster navigation and better app organization.

2. 🆕 Redesigned Icons and UI Elements

Icons across the system have received a minimalistic and modern makeover. Animations are smoother, and transitions feel more fluid, giving the entire UI a refreshed and premium look.

3. 🖼️ Better Widget Customization

Widgets are now more interactive and customizable, letting users resize, stack, or arrange them more flexibly across the home screen.

4. 📂 Larger and Smarter Folders

The new update introduces larger home screen folders with support for label customization and app previews, improving accessibility and aesthetics.

5. 🎨 App UI Enhancements

Native apps like Samsung Messages, Phone, Gallery, and Settings have been redesigned with improved accessibility, layout uniformity, and visual clarity.

6. 🔒 Improved Privacy & Security Controls

With Android 15 under the hood, One UI 7 offers granular privacy controls, including enhanced location access settings, clipboard history protection, and restricted photo sharing.

7. 🛡️ April 2025 Security Patch

Alongside the new features, Samsung has included the latest April 2025 Android security patch, ensuring your Galaxy S21 remains protected against recent vulnerabilities and threats.

🧩 Other Notable Additions

• More intuitive gestures for multitasking and navigation

• AI-powered performance optimizations for better battery life and app management

• Enhanced Samsung DeX experience with improved UI on external displays

• Smarter camera AI enhancements and photo editing tools

These features not only improve usability but also breathe new life into the three-year-old Galaxy S21 series—making it feel more in tune with 2025 standards.

📲 How to Install One UI 7 on Galaxy S21 Devices

Installing the One UI 7 update is straightforward. Follow these steps to download and install the update:

1. Open Settings on your Galaxy S21, S21+, or S21 Ultra.

2. Scroll down and tap on Software update.

3. Tap Download and install.

4. Wait while the system checks for the update.

5. If available, click on Download.

6. Once downloaded, tap Install Now and follow on-screen instructions.

Tip: Make sure your device is charged to at least 50% and connected to Wi-Fi before beginning the installation.

⚠️ Precautions Before Updating

• Backup important data using Samsung Cloud, Google Drive, or a PC.

• Ensure there is sufficient internal storage (minimum 5GB).

• Be patient during the update process—your phone may restart multiple times.

💬 User Reactions and Early Feedback

Early adopters in South Korea have praised the smoothness of the new interface, refined animations, and the stability improvements that come with One UI 7. Users particularly appreciate the fresh design language and practical improvements to multitasking and customization.

Some users have reported a slight delay in app opening speeds right after installation, but this is likely due to the system optimizing itself post-update. After a few hours of usage, most performance concerns appear to resolve.

🔄 What Happens Next?

Since the rollout has just started in Korea, Samsung will likely expand One UI 7 to international Galaxy S21 units in May 2025. Regions like Europe, India, North America, and Southeast Asia can expect the update soon—possibly with identical build numbers for their local models (e.g., SM-G991B, SM-G996B, etc.).

Keep an eye on:

• Samsung Members App

• Community Forums

• Settings > Software Update
  for update availability notifications in your region.

📌 Final Thoughts

The One UI 7 update for Galaxy S21 series is not just another Android upgrade—it's the final curtain call for a flagship series that defined Samsung’s smartphone lineup in 2021. With new UI features, enhanced customization, improved performance, and fresh security enhancements, this update ensures that Galaxy S21 devices remain relevant and reliable in 2025.

Although Galaxy S21 users won’t see Android 16, they can rest easy knowing that Samsung has provided the promised four-year OS support with excellence. With One UI 7, your Galaxy S21 is more secure, smarter, and stylish than ever.

🗣️ Are You Updating?

Have you received the One UI 7 update on your Galaxy S21 series device yet? Share your experience in the comments below and let us know your favorite new feature!