Born and raised in Cincinnati, Ohio, Dennis attended Howard University where she earned a degree in theater. Dennis' first acting role came in 1990 in the television movie A Mom for Christmas, starring Olivia Newton-John. From 1998 to 2000, she served as host on Teen Summit, a teenage talk show that aired on BET. In 2006, she had a role in the unsold Comedy Central pilot Three Strikes. That same year, she appeared on Damon Wayans' sketch comedy show The Underground. Dennis has also been on Shake It Up, A Disney Channel program.
In 2008, Dennis won the role of Janay, friend of Malik Wright (Hosea Chanchez) and soon-to-be live-in girlfriend of Derwin Davis (Pooch Hall) on the CW series The Game. She has since had roles in the direct-to-DVD film Bring It On: Fight to the Finish (2009), Hollywood Horror, and The Marc Pease Experience starring Ben Stiller. She did play Denise Roy on Spike TV's Blue Mountain State as Craig Shilo's girlfriend. Her character has been removed due to her co-star being written out of the show due to his recent arrest on drug charges.
Dennis can also be seen in a 2011 commercial for State Farm Insurance, also starring Selita Ebanks and former The Game co-star, Mehcad Brooks.