Tambyah started getting involved with the Singapore Democratic Party in 2010 and spoke as a guest speaker at the SDP rallies during the 2011 Singaporean general election.
He became a member of the SDP's Healthcare Advisory Panel in 2013.
In 2015, he became a political candidate as part of the SDP team and contested the Holland–Bukit Timah Group Representation Constituency (GRC) in the 2015 Singaporean general election.

On 26 September 2017, he was elected as Chairman by the CEC members during the Singapore Democratic Party 18th Ordinary Party Conference, replacing Wong Souk Yee.

On 30 June 2020, Tambyah was fielded as a SDP candidate for the Bukit Panjang Single Member Constituency during the 2020 Singaporean general election.
Tambyah started getting involved with the Singapore Democratic Party in 2010 and spoke as a guest speaker at the SDP rallies during the 2011 Singaporean general election. He became a member of the SDP's Healthcare Advisory Panel in 2013. In 2015, he became a political candidate as part of the SDP team and contested the Holland–Bukit Timah Group Representation Constituency (GRC) in the 2015 Singaporean general election.
On 26 September 2017, he was elected as Chairman by the CEC members during the Singapore Democratic Party 18th Ordinary Party Conference, replacing Wong Souk Yee.
On 30 June 2020, Tambyah was fielded as a SDP candidate for the Bukit Panjang Single Member Constituency during the 2020 Singaporean general election.
Paul Tambyah