Chris Froome of Britain will make his debut for the Israeli starting nation at Vuelta San Juan in January in Argentina.
Froome struggled for form last season after being injured in 2019 and was not selected for this year’s Tour.
“This marks the beginning of a much-anticipated new chapter of my career,” said Froome, 35.
The eight-day race is one of the major tournaments of 2021 after the cancel the Tour Down Under in Australia.
Froome, who started racing for Ineos (formerly Team Sky) in 2009, is still looking for the form that won him seven Grand Tour victories between 2011 and 2018.
An accident during the Criterium of Dauphine 2019 caused him to suffer multiple breakdowns, threatening his career.
it was not selected for this year’s Tour, with Ineos preferred by 2019 Tour winner Egan Bernal, who abandoned the race before level 17 after missing more than seven minutes on 15 platforms.
Israel Start-up Nation, which has been a World Tour outfit since 2020, has signed Froome on a “multi-year” contract.
The team’s new sports director, Rik Verbrugghe, said Froome is “not going to Argentina to win the race”.
“We see it as the perfect opportunity for Chris to begin the construction process towards the top of the season down the road,” he said.
Froome defeated his last race for Ineos in Vuelta a Espana last month. He finished 98th, but helped Richard Carapaz in second place.