At the 2011 general election, Khor was elected as the MP for the Hong Kah North Single Member Constituency. She defeated the Singapore People's Party's candidate Sin Kek Tong. Khor was made a Minister of State at the Ministry of Health and subsequently also served concurrently as the Minister of State at the Ministry of Manpower from 1 August 2012. From 1 September 2013, Khor was promoted to Senior Minister of State. She relinquished her appointment as Mayor of South West CDC on 27 May 2014, at the end of her Mayor's term. As of 2016, She continues to serve as the Senior Minister of State in the Ministries of Health and of Manpower, and as the Deputy Government Whip.