Diokno was born in Manila, the eldest of six children to lawyer Chel Diokno and writer Divina Aromin.
Diokno attended La Salle Green Hills for grade school and high school. He then pursued a bachelor's degree in Film and Audio-Visual Communication at the University of the Philippines - College of Mass Communication.[5]
In 2006, Diokno made the short film "No Passport Needed", which was selected for the Cinemalaya Independent Film Festival. In 2008, he made the short documentary "Dancing For Discipline," which allowed him to visit jails and detention facilities across the Philippines. It was at one such facility in Davao City that he met two brothers who inspired his first feature film.[6]
In 2023, Diokno directed and co-wrote the historical drama GomBurZa, which premiered at the 2023 Metro Manila Film Festival, where it received seven awards, including Best Director.[4] The film, which was produced by Jescom Films and MQuest Ventures, was a critical and commercial success, spending over five weeks in cinemas,[11] and debuting at number one on Netflix.[12]
During the COVID-19 crisis in 2020, Diokno produced a series of pro-bono commercials for the Department of Health to raise awareness about the virus among Filipinos with no access to the Internet.[14]