Lend Lease is believed to have beaten-off competition from BAM, Mace and Skanska to land the deal.
Work will start on site this month with completion expected in summer 2017.
The 350,000 sq ft development includes a 10-storey office block, new retail frontage and public plaza.
Dennis Wilson, Lend Lease Project Director, said: “We are excited to be working with Legal & General and further strengthening the relationship that delivered both Central Saint Giles and Legal & General’s headquarters at One Coleman Street, London Wall.
“This latest success capitalises on our strategy of winning repeat work from longstanding clients, and adds to our growing pipeline – having secured several major opportunities over the last few months.”
Simon Wilkes, Head of Business Space Development at Legal & General Property, added: “Lend Lease’s appointment on this exciting new development reflects the team’s understanding of our needs, innovative approach and shared commitments to safety, the community and sustainability.
“Following this, we feel that we now have the best team in place to deliver what is set to be a milestone development for Hammersmith as a key office location in London.”
The existing commercial building at 245 Hammersmith Road will be demolished to make way for the new scheme.