She attended John XXIII College for a year and then went to Street Hilda"s Anglican School for Girls from 1995 until her graduation in 2002. Jessica attended the National Institute of Dramatic Art where she graduated in 2007.
She is best known for her roles as Rachel Rafter on the television series Packed to the Rafters and Lily Diamond on the television series Magic City. Born in South Africa, Marais and her family lived in Canada and New Zealand before relocating to Perth, Western Australia, when she was nine. Six months after arriving in Australia, Marais" father Tony died from a heart attack while returning from a family picnic.
National Institute on Drug Abuse appearances included Ophelia in William Shakespeare"s Hamlet and Charity in Sweet Charity.
Marais was attending National Institute on Drug Abuse when she was cast in the role of Rachel Rafter on the television series Packed to the Rafters. The series became a success and was instantly renewed.
In February 2011 it was announced that Marais had left the show, with her final episode airing on 23 August 2011. Marais starred in the series from Season One until Season Four from 2008-2012.
Marais made cameo appearances in the final episode of season 4 on 20 March 2012 and in the series finale on 2 July 2013.
Marais also starred in Rai Fazio"s film Two Fists, One Heart with fellow Perth actor Tim Minchin and Daniel Amalm which was released in March 2009. After departing Packed to the Rafters, Marais relocated to Los Angeles to pursue a career in Hollywood. Marais then headed to Miami, to film United States drama, Magic City.
The series lasted two seasons.
After re-locating back to Australia, Marais portrayed Australian transgender entertainer and activist Carlotta in an biographic telefilm for ABCTV Australia. Its worldwide premiere was on 19 June 2014.