The Australian actor, who plays Rachel Rafter in the television drama, is believed to have quit her role in a bid to move to the US and break into Hollywood acting.
A spokesperson for Channel Seven told The Daily Telegraph: "After four seasons, Jess is taking a break from Rafters to explore some other acting opportunities.
"Creatively, it's great to stretch and grow as an actor. She has Seven's full support and will always be a part of the Rafter and Seven family."
Producers are believed to be leaving the door open for Marais's return after her exit from Packed To The Rafters in June, while her real-life fiancé James Stewart allegedly plans to remain on the show.