Prior to becoming a Journalist, Hennessy dabbled in acting alongside her sister. In 1988, the two appeared as twin call girls in the David Cronenberg film, Dead Ringers. They also co-starred in a film written and co-directed by Jill entitled The Acting Class.
One of Hennessy's most visible performances was uncredited. In 1995, Jill Hennessy, who played Claire Kincaid on the NBC crime drama Law & Order, made a couple of crossover appearances as Kincaid on another series, Homicide: Life on the Street. During the filming of one of these crossovers, the production schedules of both shows overlapped. As a result, Jacqueline was recruited to play Kincaid in some courtroom scenes filmed for the Law & Order episode "Corpus Delicti", which aired in January 1996.
In 2008, Hennessy was hired to narrate W Network's and HGTV's Love it or List it.
