Meadow, 21, shared a photo Monday on Instagram with Diesel's son, Vincent, 10, and his daughters Hania, aka Similce, 12, and Pauline, 5.
"family, forever," she captioned the post.
The late Paul Walker and Diesel co-starred in the first seven Fast & Furious movies. The actors played Brian O'Conner and Dominic Toretto, respectively.
Actresses Gal Gadot and Nathalie Emmanuel, who both appeared in Furious 7, showed their love for Meadow and Diesel's kids in the comments.
"Miss you all," Emmanuel wrote.
Paul Walker and Diesel were close friends prior to Walker's death in a car crash at age 40 in November 2013. Diesel wished Meadow a happy 21st birthday on Instagram in November alongside a photo of Meadow with Pauline.
"I could say that I am so proud of the person you are becoming... but the truth is I have always been proud of you," the actor wrote. "Happy Birthday Meadow! I know it's your 21st and you wanted to go big in Japan, but the family has a cake waiting for you when you get home, so hurry. Love you kid. Uncle Vin."
Diesel and his partner, Paloma Jimenez, named their daughter Pauline after Paul Walker.
"There's no other person that I'm thinking about as I'm cutting this umbilical cord," Diesel said on Today in 2015. "I knew he was there and I felt like, you know, a way to keep his memory a part of my memory, a part of my world."
The ninth Fast & Furious movie, F9, will open in theaters in April 2021 after being delayed due to the coronavirus (COVID-19) pandemic. A trailer for the movie released in January shows Dominic (Diesel) caring for his son, Brian, named after Walker's character.