Leighton Meester appeared on “Late Night With Jimmy Fallon” which is tape in New York City last night.

She was on the show to promote new movie “The Roommate” where she plays a psychopathic roommate.

The ‘Gossip Girl’ actress dazzled wearing an Emanuel Ungaro Pre-Fall 2011 look.

Her sequined floral long sleeved dress is perfect transitional look. She got the balance right unlike Emily Blunt earlier this week.

This look is in total contrast to her earlier demure look.

This is sexy without revealing too much as she only opted to show off her toned legs in this cute mini dress.

Black strappy Pierre Hardy sandals completed her look.

Credit: Style.com & Startraks Photo/Rex Features