Los Angeles County District Attorney's spokeswoman Jane Robison says Tameka "Tiny" Cottle entered the plea through her attorney on Monday.
Meanwhile, the rapper himself reported to a federal prison in Arkansas Monday, to begin serve an 11-month sentence for violating his probation on weapons charges.
Cottle was arrested Sept. 1 along with her husband during a traffic stop on Los Angeles' Sunset Strip.
The 35-year-old is not required to appear in person on the case. It will be called for a pretrial hearing on Jan. 6.
Cottle's attorney, Blair Berk, declined to comment.
Prosecutors declined to charge T.I., citing a federal judge's decision to send him to prison for 11 months and because only four ecstasy pills were found on him.
The weapons charges stem from a 2007 sting operation in which he was caught receiving three machine guns and two silencers.