The appointment was made after a pitch against undisclosed agencies, and gives the agency a new four-year contract with the company.
As part of the move, Swarm, the integrated offshoot of Rainey Kelly Campbell Roalfe/Y&R, has also been added to the museum's roster to handle project work.
The Natural History Museum called a pitch for its creative account at the end of April. James Bailey, the head of marketing at the museum, handled the pitch process.
Krow will now create a series of print, poster and digital campaigns for the museum, in an effort to boost the number of visitors to the attraction each year, as well as aim to raise awareness of its involvement in essential scientific research.
Last month, the Natural History Museum also called a pitch for its media planning and buying account, which is held by Total Media.