The 49-year-old actor and 70-year-old star made the Los Angeles premiere of their movie Guardians of the Galaxy Vol. 2 a family affair.
Diesel, who voices baby Groot in the film, was all smiles with 9-year-old daughter Hania and 6-year-old son Vincent at the event. He and partner Paloma Jiménez also share 2-year-old daughter Pauline.
"I'm probably the most excited kid in the world right now!" Hania gushed while speaking to Entertainment Tonight.
"This is a lifetime experience for me," Vincent added.
Stallone, who plays Stakar Ogord in the movie, brought wife Jennifer Flavin and their daughters, Scarlett, Sistine and Sophia, to the premiere. He is also dad to son Seargeoh and late son Sage with ex-wife Sasha Czack.
"All I know is God must hate me to give me these daughters. They're making my life hell, but in a good way," the actor told ET before confirming his daughters stole actor Liam Hemsworth's phone number out of his cell phone.
Fellow Guardians of the Galaxy Vol. 2 stars Chris Pratt, Zoe Saldana, Karen Gillan and Kurt Russell also attended the event. The movie co-stars Dave Bautista and Bradley Cooper, and opens in theaters May 5.