Walker passed away in a car crash in November 2013 when his daughter Meadow was just 15. Diesel referred to him as his brother when he mourned his death.
"I wish you could see the world right now… and the profound impact, your full life has had on it, on Us… on me. I will always love you," Diesel wrote.
Diesel is Meadow's godfather and celebrated her birthday with an Instagram post last November.
"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," he 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".
Meadow often shares throwback photos and videos of her father on her Instagram. In April, she shared a heartwarming video of her surprising him on his birthday, captioning it: "I never thought I'd share this. But it felt right. Be good. I love you. Stay safe."
The clip sees Meadow scaring Walker in his trailer.
"You just scared the hell out of me!" he says in the video before pulling her in for a hug.