Button is the third F1 title winner, alongside Lewis Hamilton and Nico Rosberg, to establish a team to race in the championship founded by Formula E co-creator Alejandro Agag.
The announcement of JBXE, which comes just 10 weeks ahead of the maiden desert event in Saudi Arabia in April, boosts XE up to a 10-team grid for its first campaign.
An initial livery render suggests Button’s team will carry over the white and fluorescent yellow scheme - an homage to his 2009 title-winning Brawn GP car - sported by the Jenson Team Rocket RJN outfit’s McLaren 720S GT3 used in the British GT Championship.
New Williams F1 senior advisor Button, who has yet to reveal his team's female driver, said: "JBXE has been a long time coming and I'm both delighted and proud to announce its formation and entry into the inaugural Extreme E Championship.
“I caught the off-road bug a few years back, which led to me entering my own team in a few races including the Mint 400 and even the Baja 1000 and I absolutely loved it!
“It was around the same time I first heard about the plans for Extreme E, which I've followed with great interest, and what Alejandro, Ali [Russell, XE chief marketing officer] and the team have managed to create is nothing short of incredible.
“In Extreme E, they've created a product that will offer first-class racing and entertainment to the fans, but also serves to highlight the impact of climate change.
“While we will of course compete to win on track, as a collective we will also work to maximise awareness while racing in places that have been damaged or affected by climate change over the years.
“Alongside the awareness piece, Extreme E themselves are committing legacy initiatives at each destination which help protect already damaged ecosystems impacted by climate change.”
“On track I’m delighted to say there are some world-class opponents to go wheel-to-wheel with and Extreme E is a world-first which sees true equality with male and female drivers both as team-mates and as opponents out on track.
Button, the 2018 SUPER GT champion alongside Naoki Yamamoto, has experience of loose-surface competition, having contested the famous Baja 1000 off-road race in 2019.
His late father John also enjoyed success in the British and Lydden Hill Rallycross Championships, finishing runner-up in both competitions in 1976.
Agag added: “I’m thrilled to welcome another major name in the world of motorsport in Jenson Button. He is one of the most popular drivers in the business and Extreme E will give him the opportunity to live out one of his long-held passions, to compete at the highest level in off-road racing.
“Jenson, alongside his peers, will give further weight to our mission to raise awareness of the global climate crisis, while doing what we love - racing.”