Within the PAP, Teo was First Assistant Secretary-General in the party's Central Executive Committee (CEC) before he was succeeded by Heng Swee Keat in November 2018.

Teo joined the Singapore Armed Forces (SAF) in 1972 and was commissioned as a naval officer at the SAFTI Military Institute in 1973.

[3] Teo made his political debut in the 1992 by-elections in Marine Parade GRC as part of a four-member PAP team led by Prime Minister Goh Chok Tong.

After the PAP team won 72.9% of the vote against three opposition parties, Teo was elected as the Member of Parliament (MP) representing the Joo Chiat ward of Marine Parade GRC.

Teo switched to contesting in Pasir Ris GRC during the 1997 general election and the four-member PAP team led by him won 70.9% of the vote against the Workers' Party.

During the 2001 general election, Teo led the five-member PAP team contesting in the newly formed Pasir Ris–Punggol GRC and won an uncontested walkover.

During the 2006 general election, Teo led a six-member PAP team to contest in Pasir–Ris Punggol GRC again and won 68.7% of the vote against the Singapore Democratic Alliance.

Teo led a six-member PAP team to contest in Pasir–Ris Punggol GRC in the 2011 general election and won 64.79% of the vote against the Singapore Democratic Alliance.