The Disney executive who oversaw the launch of streaming service Disney+ will be leaving his post to become CEO of the popular social media app.

Rebecca Campbell, Disney veteran, will be succeeding him as chairman of direct-to-consumer and international. Mayer has joined as CEO of TikTok during a pivotal time, as downloads in March surpassed 2 billion worldwide. However, he will face growing concerns about TikTok’s collection of data and whether or not it may be a national security risk.

“I am very proud of what our extraordinarily talented direct-to-consumer and international team has accomplished in creating and delivering a world-class portfolio of streaming services, particularly Disney+,” Mayer announced in a statement this Monday. “It’s truly been a privilege for me to be part of the iconic Walt Disney Co., and I am enormously grateful to Bob Iger for his trust and confidence and to Bob Chapek and his senior management team for their collaboration and support over the years.”