The company has promoted Mosseri - a 10 year veteran of the social network - from his role as vice president of product for the photo sharing app, having previously held a vice president role managing Facebook's News Feed and interface teams.
In a press release, Systrom and Krieger heaped praise on their replacement, and insisted he was a good choice to lead the business.
They said: "We are thrilled to hand over the reins to a product leader with a strong design background and a focus on craft and simplicity -- as well as a deep understanding of the importance of community.
"These are the values and principles that have been essential to us at Instagram since the day we started, and we're excited for Adam to carry them forward."
The duo added that they are looking forward to seeing what happens in the future, and gave Mosseri a vote of confidence.
They continued: "We remain excited for the future of Instagram in the coming years as we transition from being leaders at Instagram to being just two users in a billion.
"We're confident that under Adam's leadership, Instagram will evolve and improve and we look forward to the future of the product and community."