Barton Crockett, analyst at Rosenblatt Securities, told Reuters it was a "natural fit" for Meta, which extended into boss Mark Zuckerberg's "vision of personal AI" using agents.
Based in Singapore after relocating from China, Manus has sought to set itself apart from rival AI developers with what it claims can be a "truly autonomous" agent.
Unlike many chatbots which need to be repeatedly asked for things before a user can get their desired response, Manus says its service can plan, execute and complete tasks independently in accordance with instructions.
It forms part of the company's mission to "extend human reach" with general-purpose agents that can aid, rather than replace, human work.
The company said its acquisition by Meta was "validation" of its efforts.
"Joining Meta allows us to build on a stronger, more sustainable foundation without changing how Manus works or how decisions are made," said Xiao Hong, its chief executive and one of its Chinese founders, in a blog post.
"We're excited about what the future holds with Meta and Manus working together and we will continue to iterate the product and serve users that have defined Manus from the beginning."
Meta said as part of its deal it would continue to operate and sell Manus' AI service.
It marks yet another high-profile move by the Silicon Valley tech giant to cement its presence in the sector through deals with rising start-ups.
In June the company spent $14bn to buy 49% of Scale AI and secured its boss to take a lead role in Meta's development of the tech.
This came amid a wider increase in spending by Zuckerberg on the company's AI strategy, as well as reportedly luring talent from rivals like OpenAI.
