The contract is expected to be worth £350,000 per year.
The venue (formerly known as the Officers' Mess at the Royal Army Medical College, and now part of the University of Arts London) is aimed at conferences, corporate events, wedding receptions, shows and parties, and has a capacity for between 15 to 200 people. There is also an outside courtyard and gardens, with space for a marquee and up to 700 guests.
The company was praised by the college for its quality food and for its understanding of the venue, which is Grade-II listed with original features, including oak panelling and fireplaces, and is used as an educational site during the day.
Alanah Cullen, head of enterprise at Chelsea College of Arts, said: "Throughout the tender process Seasoned demonstrated its ability to work within the constraint of delivering high quality events within a fully functioning university."
Colin Sayers, chief at Seasoned, commented that the company had a proven track record of working at venues with multiple uses.
He said: "This contract reinforces our reputation as caterers that genuinely push the boundaries of food design whilst appreciating the restrictions of our surroundings."
Seasoned operates catering and management deals with a variety of London venues and events, such as the Hampton Court Palace Festival, plus a host of museums, halls, galleries and clubs.