“I love openai, and everything i’ve done over the past few days has been in service of keeping this team and its mission together,” Mr. Altman said in a post to X. “with the new board and w satya’s support, i’m looking forward to returning to openai, and building on our strong partnership with msft.”

Four board members — Ilya Sutskever, an OpenAI founder; Mr. D’Angelo; Ms. Toner, a director of strategy at Georgetown’s Center for Security and Emerging Technology; and Ms. McCauley, an entrepreneur and computer scientist — had initially decided to push Mr. Altman out.

But as the employee revolt grew, Mr. Sutskever repented in a message on X: “I deeply regret my participation in the board’s actions.” He also signed the letter. Now that Mr. Altman has been reinstated and a new board is in place, Mr. Brockman, who has worked closely with Mr. Altman for more than a decade, will also return to OpenAI. Mr. Sutskever is no longer on the board but remains an OpenAI employee.

“Ilya is thrilled that Sam is back as C.E.O. and he has been working tirelessly for days to make this happen,” said Mr. Sutskever’s lawyer, Alex Weingarten. “It is what is best for the company.”

OpenAI employees celebrated a return to normalcy Tuesday night, after five days of uncertainty. Workers had been given the week off for Thanksgiving, but many remained in the office or glued to their screens to follow the drama. “Thank god,” one employee said. “We’re so back,” said another.