During his term as mayor, Gatchalian ended the city's garbage woes and oversaw the clearing operations in the aftermath of Typhoon Ondoy.

[4][5] Gatchalian then ran for and won a position in the Senate during the 2016 elections with his campaign around the promise of passing the Free Higher Education Act.

The Gatchalian family is of Chinese descent[15] and identifies as evangelical Christian, with Dee Hua being a pastor and chairman at their own church, Jesus our Life Ministries in Barangay Maysan, Valenzuela.

[16] Gatchalian finished his elementary and secondary education at Grace Christian High School in the 1980s[17] in Quezon City and graduated with a degree in Finance and Operations Management from Boston University in 1995.

During his nine-year tenure as local chief executive, Gatchalian revolutionized good governance in the City Government of Valenzuela through reforms which eradicated corruption, fostered growth in the local business sector, and improved the provision of social services in education, health, in-city housing, and other key areas.

[36] Some of his other proposed bills during this term include acts regulating parking fees in malls and commercial areas,[37] including ROTC among the prerequisites for tertiary level graduation,[38] increasing the budget for NAIA to transform its global image,[39] abolishing the Road Board (a government agency that handled motor vehicle users' tax and road users' tax),[40] protecting passengers against abusive and itinerant taxi drivers,[41] for the declaration of candidates seeking to profit from election polls as nuisance candidates,[42] as well as a proposed bill requiring proofs of parking space to car purchasers as a means to lessen traffic congestion.

[43] In June 2015, in an event in Quezon province, Gatchalian announced his bid for a Senate seat in the 2016 general election.

In October 2015, senator and presidential candidate Grace Poe announced her senatorial slate under the coalition Partido Galing at Puso which included Gatchalian.

He challenged then-incoming President Rodrigo Duterte to make education reform a top priority of his administration.

He joined his colleague, Risa Hontiveros on leading a Senate inquiry on Bamban mayor Alice Guo over her dubious Filipino citizenship status and links to a Philippine Offshore Gaming Operator in her town which was raided for involvement in suspected illicit activities.