Elvie, which was founded with a £1.2m grant from the British Government, has secured the funding from Octopus Ventures to develop three more devices for women and expand into a further 25 countries.
The investment from Octopus Ventures, which has previously backed start-up successes including Yplan, GymBox, SwiftKey and LoveFilm.com, brings Elvie's total raised capital to £9.6m.
Its first product, released a year ago, is a pelvic floor exercise tool that connects to a smartphone app to help women strengthen their muscles.
The £149 device was designed by a team that includes a former Dyson engineer and the founder of Jawbone to help the one in three women who suffer from preventable bladder problems at some point in their lives.
Some 200m women worldwide are estimated to suffer from such problems, which could be mitigated through methods such as pelvic floor exercise, according to the National Association for Continence.
"It's a bold product and there were a lot of naysayers," says Tania Boler, chief executive and co-founder of Elvie.