In the pic, Meadow, 21, stands with Diesel's three kiddos -- Hania, 12, Vincent, 10, and Pauline, 5 -- all with smiles on their faces.
"Family, forever," the photo was captioned.
Diesel, 52, was tagged in the photo.
Walker, who died in a car accident in 2013 at the age of 40, was very close with Diesel, as were their families.
Last November, the "Guardians of the Galaxy" star wished Meadow a happy 21st birthday on Instagram with a sweet tribute.
"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. Happy Birthday Meadow!" wrote the actor alongside a picture of 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."
Per People magazine, Meadow thanked "Uncle Vin" in the comments.
"Thank you so much," she wrote. "I can't wait to see you soon. And my little angels. Love you."