[4] He is second of three sons born to Datuk Fadzil Yunus, a former director-general of the Felda group of companies[5] and Datin Fauziah Ramly, who was a senior civil servant.

After her victory in the 2013 general election, he also assumed the role of PKR Communications Director and began writing a column for The Star called On The Way.

[15] In the 15th General Election, Fahmi successfully defended his seat in Lembah Pantai with a larger majority of 13,912 votes defeating candidates from Umno, PAS and Pejuang.

[18][19] Fahmi faced criticism after questioning the findings of a survey on the government's first 100 days and accused some social media platforms of facilitating the promotion of fake news.

[20] In July 2023, the Good Vibes Festival in Sepang was cancelled by the government after the member of The 1975 rock group Matty Healy condemned the country's anti-LGBT laws and kissed bandmate Ross MacDonald during the band's performance.

The Ministry of Communications and Digital issued an immediate cancellation directive that forced the three-day festival to shut down, saying it underlined its unwavering stance against any parties that challenge, ridicule or contravene Malaysian laws.

[28] In doing so, Fahmi emphasised that over 90% of complaints made to the MCMC concerned scams, internet trafficking, sexual abuse material, grooming, illegal drug sales, access to weapons and the spread of terrorist ideology and hate speech.

[29] In December 2024, he drafted changes to the Malaysia’s Communications and Multimedia Act saying that it would enhance Malaysians’ freedom of speech partly by clarifying overly broad provisions.