Somerville officials have signed a master land disposition agreement with developer US2 for a 2.3-million-square-foot mixed-use redevelopment of 15.5 acres in Union Square.

Under the agreement, US2 agreed to pay approximately $112 million in community benefits, linkage and infrastructure payments to the city, including $2.40 per square foot of development to offset the city’s previously announced $50 million contribution toward the MBTA’s Green Line Extension project.

US2 would pay $9.3 million to purchase the 4-acre D-2 block parcel, where 150,000 square feet of commercial space and 400 residential units are planned near the planned Union Square station.

US2 estimates the project will create more than 5,000 permanent jobs.

“Together, we are going to make Union Square into a destination for employers, creating more green space, achieving housing goals with a range of affordability and preserving the neighborhood character that everybody loves today,” US2 President Greg Karczewski said in a statement.

The project would bring 1.4 million square feet of work space, including 5 percent dedicated to arts and creative industries.

The redevelopment authority voted 4-1 to approve the agreement Thursday. Zoning for the specific parcels will be determined by the Somerville Board of Aldermen, which will hold a series of hearings in coming weeks.