Covion will join Balfour Beatty's existing facilities management arm Haden Building Management.
Balfour Beatty chief executive Ian Tyler said: "This transaction is an important step in increasing our penetration of the private sector facilities management market and in broadening and deepening our range of expertise in technology, property and people services.
"The addition of Covion's clients and people will provide Haden Building Management, which is already growing strongly, with a significantly enhanced service offering in the facilities management marketplace and will establish us as a key player in the integrated facilities management field."
Covion was listed as one of the fastest growing companies in the UK in both 2005 and 2006. Based in Theale, near Reading, it has 600 staff and a client list that includes household names such as Anglian Windows, Britvic and Tate & Lyle.