This tutorial uses TWRP recovery released by Recognized XDA-Developers, upndwn4par.
Disclaimer: Rooting voids the warranty of your device. We and the developer of this rooting procedures shall not be held responsible if any undesirable outcomes may happen to your device. use of this root guide is solely at your own risk!
1. Install USB Drivers for Samsung Galaxy S3 on your computer.
2. Enable USB Debugging Mode on the phone by navigating to Settings >> Developer Options.
3. Make a backup of all your important data before following the guide.
4. Ensure the battery of the phone is charged more than 80 percent.
5. The TWRP recovery works only on the AT&T version of Galaxy S3 (SGH-I747). Applying these on any incorrect variant might brick the device. Verify the model number of the Galaxy S3 by selecting Settings >> About Phone.
1. TWRP (Mirror Link)
2. SuperSU (UPDATE-SuperSU-v1.91.zip) or the latest version
3. KNOX Removal (Mirror Link)
4. Odin 3.07
Steps to Install TWRP Recovery on Galaxy S3 (AT&T) SGH-I747
Step 1: Extract the Odin 3.07 .zip file using WinRAR/7-Zip/WinZip or any other extracting tool.
Step 2: Copy the SuperSU .zip and KNOX Removal .zip file to the SD card of your phone. DO NOT extract these files!
Step 3: Switch off the Galaxy S3. Then boot into Download Mode by pressing and holding Volume Down, Home and Power buttons together until a construction Android robot icon with a warning triangle appears on screen. Now press the Volume Up button to enter Download Mode.
Step 4: Run Odin on the computer as an Administrator.
Step 5: Connect the Galaxy S3 to the computer using USB cable while it is in the Download Mode. Wait until Odin detects the device. When the device is connected successfully, the ID: COM box will turn to light blue with the COM port number. Additionally, the successful connected will be indicated by a message saying Added.
Step 6: In Odin, click the PDA button and select the TWRP recovery .tar file. Verify that Auto Reboot and F. Reset Time checkboxes are selected. Also, ensure the Re-Partition option is NOT selected.
Step 7: Double-check and click Start button in Odin. The installation process will now begin.
Step 8: Once the installation process completes, your phone will restart and soon you will see a PASS message with green background in the left-most box at the very top of the Odin. You can now unplug the USB cable to disconnect it from the computer.
Steps to Root Galaxy S3 (AT&T) SGH-I747 via TWRP Recovery
Step 9: Boot the Galaxy S3 into TWRP recovery by pressing and holding Volume Up, Home and Power buttons together.
Step 10: In TWRP recovery, select "Install" option then navigate to the SuperSU .zip file that you copied earlier and confirm the installation.
Step 11 (optional): Return to main recovery menu and repeat Step 10 but this time select the KNOX Removal .zip file.
Step 12: Once the installation process completes, return to main recovery menu and select "Reboot".
Samsung Galaxy S3 (AT&T) SGH-I747 running on Android 4.3 Jelly Bean is now rooted successfully. Open the app drawer of the phone and check for an app called SuperSU. Verify the root status of the device by downloading Root Checker app from Google Play Store.
Note: Many Samsung devices store a flash counter that keeps track of how many times you have flashed custom firmwares to your device. Triangle Away can be used to reset the flash counter to zero.
How to Fix "Unfortunately, SuperSU has stopped"?
Step 1: Download and install the latest APK of SuperSU on your device.
Step 2: Open SuperSU app (update the binary if prompted) and allow it to disable KNOX.
Step 3: Reboot your device.
Thank's to all fellas at XDA who first tried out this rooting technique. This method was originally posted via XDA-Developers original thread.
Read also: How to Root Galaxy S3 (AT&T) SGH-I747 on Android 4.3 Jelly Bean Firmware