OPL manages and delivers commercial interior and exterior fit-out and refurbishment projects for a range of blue-chip UK customers, including Balfour Beatty itself.
Balfour Beatty described the acquisition as a strategic fit with its existing capabilities, extending the company's skill base within the fit-out market.
OPL has offices in Putney (London) and Birmingham. Sales in 2009 were £40m.
It was founded in 1994 by Neil Laughton, as chairman, and commercial director Andrew Russell.
Neil Laughton is a former SAS troop commander who has climbed Everest, circumnavigated the UK on a jet-ski, played golf at the North Pole, driven across the Sahara Desert and piloted a flying car over the Straits of Gibraltar.