Fahmi was born to a Lebanese mother from the influential Zein family and an Egyptian father, he is a naturalized Lebanese. He joined the Lebanese army in 1978. He became close to the then head of the Lebanese army general Emile Lahoud (1989-1998) and Jamil Al Sayyed who at the time was second in command of the army's intelligence service. The latter played an important role in his designation as minister of the interior in January 2020. He joined the government of Hassan Diab as an independent. Fahmi is generally considered to be a courageous military and a man who supports the institutions of the state. He held various offices in the Lebanese Army: head of the bomb squad removal unit, head commander of the Mount Lebanon military region, and the security department of the military intelligence services. Fahmi studied at the James Madison University in the United States.