Linda Yaccarino, whom Elon Musk hired to run X in 2023, grappled with the challenges the company faced after Mr. Musk took over.

Yaccarino did not provide a reason for her departure, but in an X post, she spoke fondly of the company and X owner Elon Musk.

Yaccarino led X through a tumultuous period as the social network tried to rebuild its relationship with brands concerned that their ads could show up next to offensive content.