[3] In 1982, Gamboa enlisted as a cadet in the Philippine Military Academy in Baguio and graduated as a member of the Sinagtala Class of 1986, the same batch as the two PNP Chiefs that preceded him: Ronald dela Rosa and Oscar Albayalde, as well as his successor, Camilo Cascolan.

After being assigned with the PNP Criminal Investigation and Detection Group in Quezon City in 2002, Gamboa transferred to José Rizal University where he completed his Bachelor of Laws in 2004 and was admitted to the Philippine Bar in May 2005.

[3][2] Gamboa began his military and policing career as a member of the 1st Scout Ranger Regiment of the Philippine Army deployed to Talakag, Bukidnon to suppress the local communist rebellion in the area.

[5][2] As chief of the Bukidnon Provincial Police Office based in Malaybalay, Gamboa initiated programs to significantly reduce crime and stifle the communist insurgency in the province.

As a Calabarzon PNP executive, he initiated measures to achieve a zero backlog in administrative cases of erring personnel using his lawyer skills and experience.

[2] As deputy chief, he served as task force commander for the 2019 Philippine general election who also oversaw the security preparations and implementation of the 2019 Bangsamoro autonomy plebiscite.

[5] He also helped with the internal cleansing drive of the national police by implementing preventive, punitive and restorative measures within the organization amid criticisms of the Philippine Drug War.

[3] While the position of PNP Chief remained vacant for months after Albayalde's resignation, President Rodrigo Duterte had tasked Secretary Año to supervise, lead, fix and purge the scandal-ridden national police while Gamboa stays as officer in charge.

[7] On March 5, a Bell 429 helicopter carrying Gamboa and seven other police officials crashed after it hit power cables just after takeoff in San Pedro, Laguna.

Gamboa was conscious when he was pulled out from the wreckage; he suffered injuries on his shoulder and right hand and was brought to St. Luke's Medical Center in Taguig.

Gamboa and his entourage had just finished inspecting a facility for impounded vehicles in San Pedro and were on their way to Camp Vicente Lim in nearby Calamba when the crash occurred.

[12] On March 16, due to the COVID-19 pandemic, Luzon and its associated islands were placed under enhanced community quarantine (ECQ) by President Duterte, while a state of public health emergency was earlier declared for the whole country.

[16] On April 21, Gamboa announced that those who will violate the ECQ in Luzon will not be warned anymore—instead, they would be immediately arrested and undergo inquest proceedings, citing the Bayanihan to Heal as One Act.

[17] Explaining the change in policy, Gamboa said: "We need to do this because we also want to mitigate the continued risks faced by frontline PNP personnel who are exposed to increasing number of people and motorists violating the ECQ at checkpoints."

[20] On April 21, Winston Ragos, a retired soldier with PTSD, was fatally shot by PMSg Daniel Florendo Jr. at a checkpoint in Quezon City.

Spanish expatriate Javier Parra claimed that Senior Master Sergeant Roland Von Madrona wanted to fine him for allowing his housemaid to water plants outside without wearing a face mask—a supposed violation of ECQ guidelines.

[26][27] Reacting to the aforementioned incident, Gamboa defended the actions of PSMS Madrona, saying: "You saw how big the foreigner is compared to the policeman … based on the video, it is very clear that enough force was applied.

[31] On May 12, photos of NCRPO chief Debold Sinas celebrating his birthday on May 8 went viral and drew flak online for allegedly violating the ECQ ban on mass gatherings and liquor.