He is best known for his rendition of "Bayan Ko", which became the anthem of the opposition against the regime of Ferdinand Marcos during the 1986 People Power Revolution,[2] and for his song "Anak", the best-selling Philippine music record of all time, selling 33 million copies worldwide.

"[10] Freddie Aguilar's influences include British and American folk-rock stars like Cat Stevens and James Taylor.

[9] Aguilar first began performing in public in 1973, when he auditioned and was hired to play folk songs at ₱500 per gig at the Hobbit House in Ermita, Manila.

After the album, Freddie Aguilar also sang about the injustices suffered by the powerless, poverty, and the arrogance of superpowers in a song about the U.S. and Russia.

[9] Five years after the composition of "Anak", Freddie Aguilar joined protests against the Marcos regime and began writing and performing songs that criticized the excesses of the government.

[12] Some of the songs that caused him to be banned from mainstream media include: "Kata-rungan" or "Justice" (speaking for the unjustly accused), "Pangako" ("Promise") (a leader's unfulfilled pledges to an abandoned people), and "Luzvi-minda" (an acronym for Luzon, Visayas, Mindanao, calling on Filipinos to wake up to the reality of oppression).

[12] In 1983, the assassination of Benigno "Ninoy" Aquino triggered massive demonstrations against the Marcos dictatorship, and Aguilar's rendition of "Bayan Ko" was blared on the radio and speakers mounted on jeepneys throughout the streets of Manila and the provinces of the Philippines.

[19] Aguilar, along with APO Hiking Society and other Pinoy pop musicians who took a stand against dictatorship, joined other protest singers in music and street performances as part of the anti-Marcos rallies.

On October 17, 2013, Aguilar openly admitted, in spite of the controversy that followed,[27] that he is in a relationship with a 16-year-old girl, Jovi Gatdula Albao (Muslim name Sittie Mariam), with plans to marry and even have children, as his partner insisted that she is willing to have a baby.

[33][34] On January 3, 2018, Aguilar's residence in North Fairview, Quezon City was destroyed by a fire, which was reported to have started at his music room.

[35] The fire destroyed most of Aguilar's valuables estimated at ₱15 million, including his art collection, awards, musical instruments, records, and other personal memorabilia.