Both F1 and the FIA have said the necessary sporting, technical and commercial assessments have been completed, meaning that the sport will have more than 10 teams for the first time since 2016.
"As we said in November, the commitment by General Motors to bring a Cadillac team to Formula 1 was an important and positive demonstration of the evolution of our sport," said Formula 1 chief executive Stefano Domenicali.
"I want to thank GM and TWG Motorsports for their constructive engagement over many months and look forward to welcoming the team on the grid from 2026 for what will be another exciting year for Formula 1."
FIA president Mohammed Ben Sulayem said the expansion to 11 teams was a "transformative moment" and an important milestone for the championship.
"GM/Cadillac brings fresh energy, aligning with the new FIA 2026 regulations and ushering in an exciting era for the sport," he added.
"The Cadillac Formula 1 team’s presence in the paddock will inspire future competitors and fans."
Formula 1 is entering a new engine era in 2026, with significant chassis regulation changes also, and Cadillac have a deal in place to use Ferrari engines until General Motors can produce their own.
They have also appointed Briton Graeme Lowdon to lead the team and have established a European headquarters at Silverstone.
"This announcement is the next step in getting on the grid and continues our efforts towards building a full-works team," said Lowdon.
"Through the long and thorough application process, we have never lost pace in our planning or our belief in the mission. We can’t wait to go racing and give fans a new team to cheer for."
The addition of an 11th team has been a long time coming, with American motorsport organisation Andretti being given the green light by the FIA before seeing their entry blocked by F1 last year.
That led to a change of leadership with former F1 driver Michael Andretti taking a step back and the proposed outfit dropping his surname entirely, becoming a Cadillac team backed by General Motors.