The man is undergoing treatment for his injuries, according to the Kenya Wildlife Service.
It tweeted Friday that its units have "taken control" of the lion and returned it to the Nairobi National Park.
Video posted on social media showed a black-maned lion sauntering down one of the city's busiest streets.
It later disappears from camera view as motorists honk wildly and shout that it's jumped on a man.
Other lion escapes
This is the fourth time in recent weeks
lions have escaped from the park that sits on the edge of Nairobi, Kenyan media reported
Last month, a pride of lions
made its way into residential areas in Nairobi in the dead of the night, leaving officials scrambling to find them. Some animals eventually returned to the park.
Kenya Wildlife Service spokesman Paul Udoto said residents have complicated efforts to recapture the animals. Some try to take selfies with escaped lions in the background, risking their lives for a photo, he said.
"Are you out of your senses?" he asked.
Nairobi National Park is home to leopards, buffaloes, giraffes and other animals grazing in sprawling grasslands -- the city's skyscrapers in the background. It is largely bounded by an electric fence to keep animals inside.
But its south side -- away from the city -- is bordered by a river. It's unclear whether that's the path the lions use to sneak out of the park.
Why are lions escaping?
The Kenya Wildlife Service says it is unsure why there is a surge in escapes, but conservationists cite habitat loss as the central reason.
As one of the fastest growing cities in Africa, property values are increasing in Nairobi, and the park is getting encroached on by lucrative development projects.
The government also started building a highway through a section of the park, agitating the animals with constant noise.