Kok was educated at Bukit Panjang Government High School and National Junior College and graduated from the National University of Singapore where she majored in Economics and Japanese.
Kok was first spotted in SPH MediaWorks's talent show Route to Glamour in 2001. Although she did not win, she was offered a contract with MediaWorks and later joined MediaCorp in 2005 when the two companies merged.
Kok started her acting career playing supporting roles in her starting years, frequently portraying angsty and bitchy characters such as in The Little Nyonya. She was nominated for the Best Supporting Actress category in 2009.
In August 2009, Kok starred in My Buddy as the first female lead, alongside established actors Christopher Lee and Aileen Tan. In the same year, she played Huang Jinhao in the Channel 8 blockbuster drama, Together The role of Jinhao was originally intended for Fiona Xie but it went to Eelyn when Fiona was unable to take the role due to personal reasons. Kok's performance in Together had seen her popularity rise and earned her a Best Actress nomination in Star Awards 2010.
Kok appeared in two dramas in 2010, Precious Babes and The Family Court. She also starred in the 2011 year-end anniversary series A Song To Remember opposite Joanne Peh and Qi Yuwu.