The Devil Ending in Cyberpunk 2077 implies joining forces with Hanako and siding with the Corporation. This option doesn't require much, apart from completing the final mission and choosing to collaborate with Hanako. Honestly, it's one of the easiest endings in Cyberpunk 2077. All you need to do is align yourself with the Corporation during the dialogues with Misty and Johnny. Read about other endings in Cyberpunk 2077 here. Now, WARNING: SPOILERS AHEAD!

After that, simply continue with the final mission until you reach the end. There, you will be presented with the final choice of whether to return to Earth or not. Below, read about each choice and do what you prefer (you can choose both if you want to see both final cutscenes).

Here's a brief guide on how to get The Devil Ending in Cyberpunk 2077:
Choice: Trust Arasaka.
Take the Omega blockers (Johnny won't be happy with this ending, so you'll have to eliminate him).
Make the final choice of whether to return to Earth or not.

Rewards: Johnny's Tank Top and Johnny's Aviators.

Detailed Actions

1. After calling Hanako, you will learn that she is with her brother.
2. She will send a car for you. Anders will be driving.
3. To unlock the remaining Tarot cards, ask Misty for another fortune-telling session.
4. After rescuing Hanako, head to Arasaka Tower.
5. You will learn some details about her father.
6. You will attend a roundtable meeting (board of directors), where Hanako's father will be present.
7. Battle. After the fight, Arasaka's son disappears.
8. Next, you will encounter Adam Smasher, the boss (Johnny's killer).
9. You must apprehend Yorinobu and hand him over to Hanako.
10. Mikoshi will be brought to you. This is where an angry Johnny will be waiting for us.
11. You need to return to your own body. Johnny will be standing with Alt.

• By staying there, you condemn yourself to become an engram (during the conversation with Johnny, say, "I hope Arasaka won't let me down," and then you should accept the Omega blockers). Later, you will open the Rubik's Cube and see a picture of the Devil inside. Most likely, V will be able to obtain a new body in the future.
• Returning to Earth, V will soon die from multiple injuries.