Paul, who alongside Vin, 51, led the cast of the beloved petrol-fuelled film series, died in 2013 when a Porsche Carrera GT he was travelling in crashed and burst into flames in California.
He would have turned 45 on Wednesday, September 12 - an occasion his co-star marked with a touching Instagram tribute.
The "Riddick" star posted a picture of himself with Paul and wrote: "Five years since we celebrated your last birthday... not a day goes by... Always."
The late actor's younger brother Cody Walker, 30, also honoured his sibling on the social media site.
Beneath a video announcing his annual Game4Paul video games event raising funds for Paul's disaster relief organisation Reach Out Worldwide, Cody wrote: "You would be 45 today bro. We love you, miss you and try to honor you in the best ways we can. You were generous, thoughtful and a total bada**. Always leading by actions rather than words and an inspiration to so many all over the world."
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You would be 45 today bro. We love you, miss you and try to honor you in the best ways we can. You were generous, thoughtful and a total badass. Always leading by actions rather than words and an inspiration to so many all over the world. In honor of Pdub’s birthday I am excited to announce the 4th annual #Game4Paul online charity stream set for October 11th. Proceeds support @reachoutww and its efforts. Check out the link in my bio now or go to www.game4paul.com Special thank you to: @johnbrotherton and @brettclaywell and so many others that help to make this possible every year @paulwalker #xbox #comingsoon #charitystream #paulwalker #thefastandthefurious #roww #reachoutworldwide #dogood
On the day of his death, Paul had joined his brother at a charity car show benefiting the non-profit organisation.
"Fast and the Furious" fans also posted online tributes to the star, who played police officer turned street racer Brian O'Connor in the films.
He died during the filming of "Furious 7", and Cody and their other brother Caleb Walker stepped in to help complete the movie by shooting his remaining scenes, allowing producers to digitally superimpose the late actor's face on to theirs.
His character was not killed off in the film, and both his siblings have expressed a desire to bring their brother back from the dead onscreen by filming scenes for new movies.