PRWeek revealed exclusively in November last year that the Manchester-based sports brand was reviewing its consumer PR brief, formerly held by seven-year incumbent Exposure.
A statement from Exposure said that the agency had 'mutually agreed' to part company with the brand at the end of 2011.
It is understood that Frank fought off competition from two other agencies in the final pitch process and will start work with immediate effect.
The brief is thought to encompass both Umbro's sport and lifestyle ranges.
Catherine Rees, Umbro’s head of comms, said the PR review was not part of a new strategy for the sports brand, but that it was keen to emphasise its credentials as a 'football culture brand'.
Umbro first became the official kit supplier of the England national football team in 1952 and signed a new ten-year deal in 2009 to provide the kit for current Premier League leaders Manchester City.
Umbro, which became a subsidiary of sports giant Nike in 2008, specialises in football performance and sports lifestyle wear.