Tin made her electoral debut in the
2011 general election as part of a five-member PAP team led by then-
Senior Minister Goh Chok Tong, contesting in
Marine Parade GRC; said team won 56.65% of the vote against that of the
National Solidarity Party (NSP) led by
Cheo Chai Chen. In an article about NSP candidate
Nicole Seah and her popularity on social media, the
Asia Sentinel claimed that, having been a member of the
Young PAP at the Ulu Pandan branch for seven years, Tin was fielded by the PAP as a candidate to attract the "unpredictable" youth vote through social networking sites. She was instead made fun of for her youth and perceived immaturity. On 1 June 2011, Tin announced on her Facebook account that she had resigned from her senior associate position with
Ernst & Young, where she had worked for four years, to focus on her parliamentary responsibilities full-time. Tin also earned a degree as an Executive Master of Business Administration at the University of Chicago Booth School of Business during this period. During the
2015 general election, Tin's MacPherson division in Marine Parade GRC was carved out as an SMC; she ran against Bernard Chen from the
Workers' Party (WP) and Cheo, the leader of the NSP team for Marine Parade GRC in the previous election. Cheo's campaign suffered major damage when he described Tin's new role as a mother as "her weakness" in the campaign. Facing public backlash, he later claimed that this comment was meant as a joke. Tin won 65.58% of the vote, compared to Chen's 33.6% and Cheo's 0.82%; Cheo lost his electoral deposit for not receiving at least 12.5% of the vote. During the
2020 general election, Tin retained MacPherson SMC with 71.74% of the vote against
Goh Meng Seng, the founder and leader of the
People's Power Party (PPP). She was later appointed as Chair of the Government Parliamentary Committee for Communications and Information in the
14th Parliament. Prior to the
2025 general election, MacPherson SMC was subsumed into the newly formed
Marine Parade–Braddell Heights GRC; Tin was thus fielded as part of a five-member PAP team. As no other teams were nominated, a
walkover in the GRC was declared on Nomination Day, 23 April 2025, contrary to expectations that the WP would contest there. Tin was later appointed as Chair of the Government Parliamentary Committee for Transport. ==Personal life==