Ong was born and raised in Australia. In her late teens she began her modeling career.
In 1999, Ong was signed by Jackie Chan to Media Asia in Hong Kong where she started a film career. She starred in her debut film Gen-X Cops. The success of Gen-X Cops was followed by a lead role in Rave Fever, an independent movie that established her as a serious actress.
She went to Hollywood where she had a small part in Pearl Harbor in 2001, but then shifted her acting career to Los Angeles where she was cast for several guest appearances in US TV series Las Vegas and Entourage.
Based in Singapore since 2004, Ong has co-starred with Thai actor Gof Akara and Sharon Au in Channel 5 drama Tiramisu. She is also a host for AXN, currently hosting and writing for eBuzz, a weekly entertainment magazine programme where she interviews international celebrities.
She is a World Vision Singapore Goodwill Ambassador, travelling to Phuket, Thailand to learn more about poverty, HIV/AIDS and child prostitution issues. On her return, she participated in various World Vision events to help promote the charity. In December 2007, she was involved in a nation-wide campaign for World AIDS Day called "One Life Experience".
- "Episode 1".
- Kelvin Yang (1 Feb 2007). "One Life Experience (OLE): The Student Volunteer’s Perspective".
- "Buy a M.A.C VIVA GLAM lipstick on December 6, 2008, and support a child living with HIV in Singapore through school!". World Vision Singapore. 1 Dec 2008.
- "SAMSUNG OMNIA ON AXN'S EBUZZ".
- "Jaymee Ong's all revved up for the Singapore Grand Prix". 24 September 2008.