The actor opened up to ET at the star-studded premiere of 'Avengers: Endgame' in L.A. on Monday.
The actor, who plays the beloved tree monster Groot in the Marvel Cinematic Universe, walked the star-studded red carpet at the premiere of Avengers: Endgame on Monday, where he stopped to talk with ET's Kevin Frazier about his experiences with being a part of the celebrated franchise.
Since Diesel only provides the voice for Groot, the star isn't on set with his fellow Guardians, but that hasn't kept him from making some close friendships over the years.
"Probably my favorite in the whole cast [and] the closest in my family is Zoe Saldana," Diesel shared. "Hence Avatar. Hence why I'm doing Avatar, or one of the reasons."
While the long-awaited Avatar sequel isn't slated to hit theaters until December 2020, the star says he's always keeping his eye on the future, and he's always got his mind on new and exciting projects.
"I'm always torn, you know. As much as I can celebrate Avengers right now, I've got [Fast and Furious 9] coming in 2020. We got to grind man. We got to grind," Diesel shared.
However, he made sure to put a lot of care and effort into his outfit for Monday's big premiere, donning an incredible leather jacket designed to look like it's covered in thick layers of mossy tree bark, an homage to his MCU character.
"We do it in the name of love and cosplay," Diesel said, after joking that he should have brought a towel to wipe down the sweat, considering how hot it was in his getup.
"All those [fans] out there, when you come into this premiere, you see so many people invested. They created costumes, they're wearing it out there in the intense heat," Diesel reflected. "And I felt like just jumping in with them and being a part and repping with them. Hence the bark."
Avengers: Endgame hits theaters April 26.