Prior to entering politics, Teo had worked at the Economic Development Board (EDB), Agency for Science, Technology and Research (A*STAR) and National Trades Union Congress (NTUC).

She made her political debut in the 2006 general election as part of a five-member PAP team contesting in Bishan–Toa Payoh GRC and won by an uncontested walkover.

[5] In November 2005, Teo also took on the role of Director of Human Resources at the Administration and Research Unit of the National Trades Union Congress (NTUC).

[7] Teo made her political debut in the 2006 general election when she contested in Bishan–Toa Payoh GRC as part of a five-member People's Action Party team.

[8] Following the 2011 general election, Teo along with Wong Kan Seng, Hri Kumar, Ng Eng Hen and Zainudin Nordin contested in Bishan–Toa Payoh GRC and won about 56% against the Singapore People's Party.

She was promoted to Senior Minister of State at the Ministries of Finance and Transport on 1 September 2013, and switched to representing the Bishan North ward of Bishan–Toa Payoh GRC.

[13] As Minister for Communications and Information, Teo introduced the Online Safety (Miscellaneous Amendments) Bill which was passed unanimously in Parliament on 9 November 2022.

[15] In a media interview in October 2016, Teo responded to questions of whether Singaporeans were getting their Housing and Development Board flats early enough in order to start a family, stating that one "does not need much space to have sex".

So, lesson learnt.” In April 2022, Teo moved a motion to endorse the first-ever White Paper on Singapore Women's Development in Parliament.

She further claimed that she would buy whichever brand of milk powder approved for sale by the Agri-Food and Veterinary Authority that was cheapest for her own children.

The Bill prohibits the online publication of deepfakes and digitally manipulated content of political candidates during the election period.