Created in 2015 by the broadcaster Lauren Laverne and the journalist and author Sam Baker, The Pool claims more than 850,000 monthly unique users. It has won plaudits and prizes, in particular its publishing schedule, which it says is designed to fit into the lives of "smart, busy women".
Finn has been taken on to showcase The Pool's commercial partnership opportunities and position it as a dynamic digital brand.
Jo Morrell, CCO of The Pool, said: "The Pool is all about communicating meaningfully to a valuable audience. Commercially we do this through multimedia packages of content where brands can tell their story in a safe environment.
"Our appointment of Finn, with its expertise in the media and marketing landscape, will help advertisers discover why The Pool, with its highly engaged fan club of an audience is such a fantastic opportunity to communicate with real impact to women."
The account will be serviced by Finn's media team, which was created last year when it hired former Braben MD Matt Bourn to open a London office. Work began this month. The Pool did not previously have an agency for this work.
Bourn said Finn was "excited to be working with a business redefining the expectations of what media can be in the mobile age".