Dory Chamoun is the elder son of the late Camille Chamoun (1900–1987), who was President of Lebanon from 1952 to 1958. An industrialist by profession, he initially showed much less interest in politics than his younger brother, Dany Chamoun. Like his father, who had no sympathy for, and disliked, the Palestinians, Dory held similar views and in private referred to the Palestinians as a race of cowards whose refugee existence in Lebanon was deserved – "If it's necessary we will chuck the Palestinians into the sea. They will pollute it but that's too bad." During the Lebanese Civil War, Dory briefly replaced his brother Dany as commander of the NLP's military wing, the Tigers Militia, between July-August 1980, prior to its disbandment by order of their father following the Safra massacre perpetrated by the Lebanese Forces (LF) led by Bachir Gemayel, which eliminated the backbone of the NLP militia and incorporated the rest into the LF structure.
After Dany was assassinated in October 1990, in what is qualified as an "unfair trial" by several organizations such as Amnesty International, Samir Geagea, the Christian leader of the Lebanese Forces, was subsequently tried for the murder. The fairness of the trial was challenged by Dory who declared publicly on 25 April 2005 that he believed Geagea to be innocent and demanded a new investigation to uncover the real assassins, whom he suspected of being Syrian agents. Nevertheless, he agreed to take over the leadership of the National Liberal Party, which his father had founded in 1958 and which Dany was leading at the time of his death. He has since travelled extensively, visiting Lebanese communities in France, Canada, Australia, New Zealand, and the United States, encouraging them to oppose the Syrian military occupation of Lebanon. He is known to be wary of foreign support; he has stated publicly that he does not trust Israel, which he accuses of "abandoning" Lebanese Christians at a time when they depended on Israeli aid, and has frequently expressed doubts about the sincerity of American and French demands for a withdrawal of Syrian forces from Lebanon. He has expressed deep disappointment that countries to which the Lebanese opposition has looked for support have not, in his opinion, lived up to their expectations.
Chamoun led the National Liberal Party in its boycott of the last three parliamentary elections (1992, 1996, and 2000), which he claimed were gerrymandered and rigged to produce a pro-Syrian majority. Since the assassination of former Prime Minister Rafik Hariri on 14 February 2005, he has been a prominent participant in the Cedar Revolution protests that have swept Beirut, calling for the total withdrawal of all Syrian troops from Lebanese territory, the resignation of the pro-Syrian government, and the holding of free and fair parliamentary and presidential elections.
Chamoun's political boycott did not extend to municipal politics. He himself served as Mayor of the Deir el-Qamar municipality from 2004 until his election on the parliament seat for the Chouf in 2009.
His eldest son, Camille, is also politically active and was an unsuccessful parliamentary candidate in the general election held in May and June 2005.
On 27 January 2006, Dory Chamoun announced his candidacy for the vacated Maronite seat in Lebanon's Baabda-Aley by-election alongside reporter May Chidiac who was also running for the same post. However, the seat went to Pierre Daccache, whom most of Lebanon's Christian parties accepted as a consensus candidate.
On 8 June 2009, Dory Chamoun was elected member of parliament for the Maronite seat in the Shouf area.
On 2 November 2012, Dory Chamoun suffered a heart attack. He was transferred to St.Charles Hospital at Fiyadieh whereby he underwent an angioplasty surgery.
On 5 March 2013, Dory Chamoun's wife Nayla Gabriel Tabet died. She was 78.