The firm has bought FME Property Solutions, a firm based in Sheffield and Darlington with a focus on the retail, hospitality, leisure and healthcare sectors.
The business capability will remain in place and will be integrated with the Bellrock maintenance and engineering services division, led by the managing director Stuart Davies.
Bellrock said the deal "completes our national critical asset maintenance footprint" and follows eight successful acquisitions over the last 26 months it completed along with investor Horizon Capital.
"FME’s technical skills and customer base offer the perfect complement to the service that we currently deliver in London and the south east," said Bellrock chief executive David Smith.
In September, Bellrock announced a restructure to simplify its business following the series of acquisitions.