Monica Keena was born in Brooklyn on May 28, 1979, to Bill and Mary Keena and was little sister to Samantha, the Keenas' first daughter. Growing sup, Monica shone in all things arts. Dance, singing, acting, and drawing. At 13, Keena enrolled in the prestigious LaGuardia school for acting and made it. At age 15, she had a small role in her first film, and that was followed by a series of TV movies, such as First Daughter (1999) and the A Promise Kept: The Oksana Baiul Story (1994). Monica starred in her first movie, Ripe (1996), at 16 and considers that her favorite role, as of now. In 1998, she premiered on the WB's Dawson's Creek (1998) as truth-telling "Abby Morgan" and later left the show when she "got bored playing one character".

Today, Monica continues to make movies like Freddy vs. Jason (2003), Man of the House (2005), and Fifty Pills (2006). In her free time, she enjoys skating.