Former world champion Jenson Button has joined Williams in the role of senior adviser as the flagging Formula One team look to revive their fortunes on the track.

Once a Grand Prix powerhouse, British outfit Williams have finished bottom of the F1 constructors' championship for the past three seasons.

Team founder Frank Williams sold Williams to U.S. investment firm Dorilton Capital last year with his daughter, Claire Williams, stepping down from her role as the de facto team principal.

British racer Button launched his Formula One career with Williams in 2000.

He took part in 305 Grands Prix – winning 15 of them – and became the drivers' world champion with Brawn in 2009.

Now, the 41-year-old will provide guidance to the team and support the development of Williams' drivers.

Button, who retired from F1 in 2017, said Friday: "I am so delighted to once again be able to say that I've signed for Williams.

"Back when I was 19 it was a moment that changed my life and, despite the fact it was over 20 years ago, I already feel like I never really left.

"Sir Frank Williams showed faith in me which I will be eternally grateful for and I am incredibly excited to have the chance to come back and help the team as it strives once more for success.

"There's a lot of hard work to be done, but I have no doubt the future is incredibly bright for this fantastic team, and I can't wait to get started."

One of the drivers whom Button will be working with is 22-year-old compatriot George Russell.

"Welcome back mate, looking forward to working with you," tweeted Russell, who stood in for Mercedes Lewis Hamilton at last season's Sakhir Grand Prix after the world champion contracted the coronavirus.