It is understood that Shearman won the client in a tendering process after San Francisco-based Levi's decided it needed a law firm with a West Coast presence. Levi's also sought a firm with a strong banking practice as the company is undergoing a major financial restructuring in a move to reduce its $1.8bn (£1.1bn) debt burden.
It is not clear how long Wachtell Lipton was primary adviser to Levi's. Highly-rated partner Patricia Vlahakis was most often connected to the company.
Shearman was recommended to Levi's by its financial advisers, which include Salomon Smith Barney and Bank of America.
Late last year, Shearman acted for the group on the issuance of $425m (£264.7m) worth of senior debt, which it is hoped will relieve some of the pressure on Levi's finances as at least two tranches of bank debt or bonds are set to mature this year.