In his tweet, Dorsey said that the company's chief operating officer Adam Bain would take on responsibility for all revenue-related product teams as well as the media and human resources teams on an interim basis, while chief technology officer Adam Messinger would take on oversight of engineering and consumer product, design and research, user services and Fabric, Twitter's mobile development platform.
Dorsey said that he would partner with Messinger "day and night to make sure we're building the right experiences."
Twitter, which has just over 300 million users, had its slowest user growth in 2015 and was eclipsed by photo-sharing app Instagram, owned by Facebook, which surpassed 400 million users last year.
The social media firm is under increasing pressure from shareholders to increase revenues and become more aggressive against competitors including Facebook and younger rivals such as Snapchat. It may be looking to expand beyond its 140 character tweets in a bid to make its service more appealing to wider audience.