Born on the 25th of October 1952 in Ain al-Remaneh, a suburb of Beirut, to one of the major Maronite families based in Bshari, he got involved at an early age in the largest Christian party in the country, the Kataeb party. However, it was not until the last years of his medical studies at the American University of Beirut (AUB) and the breaking out of the fighting in 1975 that he interrupted his studies to help defend the Kura region in northern Lebanon. It was in reaction to the fighting between Christian militia and the Palestinian-Muslim-leftist alliance that he helped reorganize the party militia in the north (Bshari, Kura, Zgharta) until the Syrian army entered the region and he could return to his studies. In 1978 at the request of Bashir Gemayel, he helped the newly formed Lebanese Forces (LF) on a temporary basis until he got wounded and sent to France to recuperate.

From the time of his return to Lebanon until 1983 Dr. Geagea became responsible for both the LF and the Kataeb party along the northern front. He opened training centers, reorganized the youth and developed fortifications opposite Syrian positions. After the “mountain war” and his continued leadership in the LF his opposition to the Christian establishment, which in his opinion dedicated itself to personal profits at the expense of the public interest, became widely known leading to his expulsion from the Kataeb party.

A series of upheavals in the LF led to the resignation of the then-commander, Fouad Abu Nadir and the appointment of Elie Hobeika as head of its executive committee and Dr. Geagea as chief of staff. However on the 15 of January 1986, Samir Geagea led a movement that removed Elie Hobeika due to his having signed the so-called « Tripartite Accord » with Syria and became commander himself. Since every sector of Christian opinion was also opposed to the accord, he was resorted to full membership in the Kataeb and was elected permanent member of the political bureau of the party.

It was the actions he undertook and the programs he developed that he would become famous for later on. He reorganized the LF and established standardized bases of recruitment, selection, training, and promotion and founded the first formal LF military academy at Ghusta. At the same time, the LF became for the first time a political movement with clear-cut socio-economic objectives and with friendly and cooperative ties to many foreign countries. The LF also began the most ambitious and systemic social welfare program ever undertaken in Lebanon and intended to help the disadvantaged and displaced.

When the war ended in 1990 with the signing of the Taef agreement, sponsored by the Arab League, Dr. Geagea dismantled his military machine and transformed the LF into a political party in 1991. Between 1990 and 1992, he was offered twice a ministerial position, which he refused. Instead, Dr. Geagea demanded the complete implementation of the Taef agreement which called for the deployment of Syrian troops to the Bekaa Valley followed by a complete withdrawal from the Lebanese territories. In reaction to the lack of efforts to implement the redeployment, Dr. Geagea boycotted the parliamentary elections of 1992 in protest. This was the turning point for the LF, since the government initiated a crackdown on the supporters of the LF and began a campaign of systematic arrests and harassments which ended in Dr. Geagea being arrested for the bombing of the Our Lady of Deliverance Church in 1994.

Although he was acquitted of the bombing, he was convicted on charges committed during the 1975-90 war for which others received general amnesty under the Taef Agreement. Dr. Geagea has been in solitary confinement in an underground cell at the defense ministry compound in Yarze where he is serving three life sentences. His supporters consider him a political prisoner and are calling for his release.