[Fire HD 8 and HD 10 General] SirHappyCatIII:
Edit: Someone pointed out the title is not completely accurate, so I changed it to be more descriptive and I will add a list of devices this root method will work with here

Edit2: Thanks to [MENTION=8978978]Rortiz2[/MENTION] for the automated method! You can download it here! Simply extract the files and run MTK-SU.bat to install the SuperSU app and root your device. Once you reboot after the batch script has completed, simply open SuperSU, go to settings, and ensure that default root access for apps is set to grant.

Fire HD 8 8th gen (2018) (thanks [MENTION=9667509]xyz`[/MENTION])

Fire HD 8 7th gen (2017)

Fire HD 8 6th gen (2016) (thanks [MENTION=6680544]bibikalka[/MENTION])

Fire HD 10 7th gen (2017) (thanks [MENTION=6680544]bibikalka[/MENTION])

Fire TV 2 2015 (mt8173-based) (thanks [MENTION=4556232]el7145[/MENTION]) -- up to firmware 5.2.6.9

Fire 7 9th gen (2019) (thanks [MENTION=4914529]Michajin[/MENTION])

Before trying this root method, please read through this entire post: 5 and make sure it will work for your device!

Note: I did not create these methods, all credit goes to [MENTION=8132642]diplomatic[/MENTION] and [MENTION=4584276]dutchthomas[/MENTION]

I simply wanted to put it into a single forum post with easy instructions.

With that out of the way, lets get started.

Only use this for Fire OS 5.x.x.x, I haven't tested it with the latest version, but it should still work.

First, follow these instructions by diplomatic:

After you have verified that you have access to a root shell (The 'shell@giza:/ $' will change to 'shell@giza:/ #) you can follow these steps by dutchthomas:

1. Install SuperSu from Playstore (if you do not have the playstore installed, you can follow the guide by [MENTION=4859884]Gilly10[/MENTION] here https://xdaforums.com/amazon-fire/general/how-to-install-google-play-store-fire-t3486603)

2. Download SuperSu and unzip somewhere (download the .zip from here)

3. Inside the UPDATE-SuperSU-v2.79-20161211114519.zip there should be an arm64 folder. Copy that folder to your platform-tools folder

Most of this is just going to be copy paste commands

4. adb push arm64/su arm64/supolicy arm64/libsupol.so /data/local/tmp

5. adb shell

6. cd /data/local/tmp

7. ./mtk-su

8. The $ after shell@giza should change to a #, if it doesn't, close the terminal and start again from step 5.

9. mount -o remount -rw /system

10. cp /data/local/tmp/su /system/xbin/su

11. cp /data/local/tmp/su /system/xbin/daemonsu

12. cp /data/local/tmp/supolicy /system/xbin/

13. cp /data/local/tmp/libsupol.so /system/lib/

14. cp /data/local/tmp/libsupol.so /system/lib64/

15. chmod 0755 /system/xbin/su

16.

chcon u:object_r:system_file:s0 /system/xbin/su

17.

chcon u:object_r:system_file:s0 /system/xbin/su

18.

chcon u:object_r:system_file:s0 /system/xbin/daemonsu

19. daemonsu --auto-daemon

20. Back on your device, open the SuperSU app and allow it to update its binaries.

After updating the SuperSU binaries, reboot your device. Once you are back to your main screen, open SuperSU, go to settings, Then scroll down to Access. Click the [Grant] option for Default Access. You need to do this because for unknown reasons the Kindle Fire is unable to show the root access popup. Your device is now fully rooted!