Endless LLP completed the acquisition of Victoria Plum from TPG Capital for an undisclosed amount.
Matthew Jubb, partner at Endless will join the online bathroom retailer's board of directors.
The investment is the latest from the £525 million Fund IV.
Law firm Squire Patton Boggs served as adviser, while Grant Thornton acted as tax adviser to Endless.
Victoria Plum was founded in 2001 and provides a range of predominantly own-branded bathroom products and accessories.