Before dealing with politics Fneish worked as a teacher. He became a member of the Hezbollah's 15-member central committee. In 1992, he was elected as a member of parliament for Hezbollah representing Bint Jbeil. He also won the same seat in the elections held in 1996 and 2000. He also ran for the seat in the 2005 general elections and got the highest votes in Tyre, namely 154,056 votes, surpassing Nabih Berri by about 1,000 votes. He was energy minister from July 2005 to November 2006. Prior to his appointment as energy minister, he served as a municipal council member in Tyre.
He was one of Hezbollah's six representatives in the government led by then prime minister Fouad Siniora until he and other Hezbollah members resigned from office in 2006. The reason for their resignation was Siniora's eagerness to sign the UN draft plan for the foundation of the Special Tribunal for Lebanon, which would search the assassination of Rafik Hariri, who was killed on 14 February 2005.
In the 2009 Lebanese general elections, Fneish won again a seat from Tyre as part of the 8 March alliance list. Then, he was appointed state minister for administrative reform in the cabinet of Saad Hariri, being one of two Hezbollah-backed ministers. The other Hezbollah minister in Hariri's cabinet was Hussein Al Hajj, in charge of agriculture ministry.
Fneish is married and has seven children.
- "Profiles: Lebanon's new government". Lebanon Wire. 12 July 2008. Retrieved 12 January 2013.
- Hamzeh, A. Nizar (1993). . "Lebanon's Hizbullah: From Islamic Revolution to Parliamentary Accommodation". Third World Quarterly 14 (2): 321–337. Retrieved 22 August 2013.
- "Opposition Candidates Win Elections". APS Diplomat Recorder. 9 September 2000. Retrieved 10 March 2013.
- "Hezbollah Sweeps Vote in Southern Lebanon". Asharq Alawsat (Beirut). AP. 5 June 2005. Retrieved 23 April 2013.
- Khashan, Hilal (Winter 2011). "Saad Hariri's Moment of Truth". Middle East Quarterly. XVIII (1): 65-71. Retrieved 11 March 2013.
- Nation unites for heroes' homecomings Daily Star
- David S. Sorenson (12 November 2009). Global Security Watch—Lebanon: A Reference Handbook. ABC-CLIO. p. 72. ISBN 978-0-313-36579-9. Retrieved 16 January 2013.
- "New parliament composition". Lebanese Information Center. Retrieved 21 January 2013.
- "Lebanese president announces national unity cabinet". M & C News. 9 November 2009. Retrieved 21 January 2013.