A member of the country's governing People's Action Party (PAP), he has served in the Cabinet since May 2014 as the Minister for Manpower (May 2014 – May 2015) and the Minister for Social and Family Development (May 2015 - Sept 2017).
He has been a Member of Parliament (MP) representing the Marine Parade Group Representation Constituency since May 2011.
Before entering politics, he served in the Singapore Army, rising to the rank of Brigadier-General.
On 5 September 2017, Prime Minister Lee Hsien Loong announced he will nominate Tan as the next Speaker of the Parliament of Singapore.
Tan's new role comes following the resignation of Halimah Yacob as Speaker to contest in the Presidential Elections 2017.
He was formally elected on 11 September 2017 as Singapore's 10th Speaker of Parliament.
Tan is also the President of the Singapore National Olympic Council, a position which he has held since 2014.