He is also the nephew of television host Jeanne Young and a cousin of actor Onemig Bondoc and guitarist Ira Cruz.

With showbiz being part of the family's life, Gus' first job after college was as Associate Producer and Sales Manager of the popular television show Spin-A-Win.

The initial years of Gus’ political career were focused on youth empowerment and development, which he pursued through collaboration with the Sangguniang Kabataan.

He is the only person to serve as a councilor under the four post-martial law Parañaque administrations – Ferrer, Pablo Olivarez, Marquez, and Bernabe.

Tambunting won by a landslide victory, besting the incumbent in 15 out of 16 barangays and a winning margin of close to 20,000 votes.

In Congress, Tambunting was a Vice-Chairperson of the Committee of Trade and Industry and a Member of the Committees of Appropriations, Banks and Financial Intermediaries, Civil Service and Professional Regulation, Ethics and Privileges, Human Rights, Labor and Employment, Legislative Franchises, Metro Manila Development, National Defense and Security, Natural Resources, and Ways and Means.

Gus has used his place in Congress to express opinions on various issues, such as the chronic traffic situation, the proposed Bangsamoro Basic Law, the spread of HIV-AIDS in the Philippines, among others.

Known as one who collaborates effectively with his colleagues in working for meaningful legislation, Gus was the author or co-author of 1,167 proposed measures during the 17th Congress.

In 2022, after Joy chose not to run again, she supported his bid for a comeback, which he won, this time as a member of the National Unity Party.

During the 19th Congress, Tambunting serves as the chairperson of the House Committee on Legislative Franchises, wherein he oversaw the investigation into Sonshine Media Network International's (SMNI) compliance with broadcasting laws amidst allegations of misconduct.

During his life as a private citizen, he excelled as a businessman and continued serving his community where he concentrated on the family-run business, Superior Maintenance Services, which was expanding to Visayas and Mindanao.