The district attorney announced the charge Friday, CNN reported.
Cottle, 35, known as "Tiny," was arrested last month along with her husband, whose real name is Clifford Harris, when officers found suspected drugs during a traffic stop in West Hollywood.
She is accused of possessing MDMA, commonly known as ecstasy, according to the court filing.
Drug charges against Harris, 29, were dropped Monday, but he still must report to federal prison by next Monday for an 11-month sentence imposed by a judge who ruled his arrest and subsequent failed drug test violated his probation on a weapons conviction.
Cottle was a singer-songwriter with the R&B group Xscape before meeting T.I. nine years ago. They married earlier this year after he completed a one-year prison term.
She also starred in the BET reality series "Tiny and Toya," which followed her life in Atlanta.