The 28-year-old fashion student is dressed in black shorts, a matching peplum top and a polka-dot shawl as she poses next to her sister in the snapshot.
Bynes' post breaks her two-month silence in the social media site. The She's The Man star last posted to Twitter in April when she shared several bikini shots of her spring break vacation in Mexico and thanked fans for their birthday wishes.
The former Nickelodeon star -- who spent six months between the hospital and rehab last year --recently completed her fist quarter at the Fashion Institute of Design and Merchandising in Orange County.
2014: The Year in Music [PHOTOS]