At Laing O’Rourke Mr Mullins he had responsibility for delivery of the shell, core and envelope of Heathrow Airport’s new £1bn Terminal 2, which opened to passengers last month.
At GB Building Solutions he will take charge of the offices in Sunbury and Rugby.
GB operations director Peter Smyth said: “Steve joins us at an exciting time for GB as we accelerate plans to grow our presence in the central and southern regions. He is a passionate supporter of continuous improvement and innovation, and brings with him a detailed knowledge of off-site manufacture, health and safety and client facing delivery.
“Steve is a strong addition to our senior leadership team and will offer a commercially creative approach to new initiatives and problem solving.”
Mr Mullins is a fellow of the Chartered Institute of Building and a chartered environmentalist.