Upon her completion of O-Level examinations at Damai Secondary School in Singapore,[3] Ong moved to Japan to further her studies as well as her career as a solo artist.
Ong, by then likened to Seiko Matsuda, had won a singing contest and was signed to Japanese recording company S2S Pte Ltd at the age of 15.
[4] On 17 November 2004, Olivia sang Majulah Singapura at the 2006 FIFA World Cup Asian qualifying rounds (Japan vs Singapore)[8] at Saitama Stadium 2002 before the kick-off.
In 2009, Ong was signed to Taiwanese record company HIM Music and became a big hit back in Singapore after she sang the theme song of the Peranakan-themed drama serial, The Little Nyonya.
In 2011, Ong recorded a duet, "最後一眼" (Just One Look), with label mate Aaron Yan of Fahrenheit, which was released in his debut EP The Next Me.