Pampanga province, 60km north of Manila, is known for being a centre of prostitution and illegal gambling and has long been lorded over by two opposing political families.
It is also the home province of the Gloria Macapagal Arroyo, the Philippine president.
"It was an extraordinary situation of a moral decay," Panlilio said, blaming the province's problems on a "culture of corruption".
So against the rules of Catholic leadership – and breaching the constitutional divide between church and state – he took a break from his priestly duties, ran for governor, and won.
Panlilio defeated Lilia Pineda, the wife of an alleged "gambling lord" and the candidate backed by Arroyo. He also beat incumbent Mark Lapid, an actor and son of a senator who has been implicated on corruption charges.
"I believe my entry into politics far transcends the church and state's so called boundaries," he told Al Jazeera after his win was confirmed.
"It's a very meaningful kind of service to the people, I believe."
With the help of thousands of volunteers, the priest ran an atypical campaign with no political machinery and no funding.
Archbishop Angel Lagdameo, the president of the Catholic bishops' conference in the Philippines, congratulated him but also called his case an "exception" and said the church wanted "to keep it that way".
But Panlilio has also made some enemies, some of whom have made threats against his life.
In his new role, rather than his priestly vestments, he wears a bullet-proof vest and has bodyguards everywhere he goes.