Southampton did not reveal the deal value but said the partnership will also see LD Sports' logo on the front of the Under-23s' and Under-18s' shirts, along with the various squads' training kit.
The deal is part of Southampton's attempt to broaden their appeal in China under the ownership of Jisheng Gao.
"It's an exciting challenge, and we are looking forward to using our growing credentials and awareness in China, as well as our content and digital marketing expertise, to help the brand achieve its business objectives over the next three years," David Thomas, the club's commercial director, said in a statement.
Southampton finished 16th in the Premier League this season with 39 points from 38 matches.
(Reporting by Hardik Vyas in Bengaluru, editing by Ian Chadband)
