Khoury was born in Mazraat Al Toufah, Zgharta District, Lebanon into a Maronite Christian family. He is the third of five children born to Tanyous and Naseema Khoury. He has two older sisters, Leena and Mona, and two younger brothers, Claude, who works as a TV director, and Dany, a music arranger. In 1986, Khoury enrolled at the Université Saint-Esprit de Kaslik in Lebanon where he studied piano, Musicology and Music History. During his university years, he won a prize in a music compositioncontest. The award was presented to the singer by former Lebanese President Amin Gemayel. On his first album, Kasak Habibi, which was released in 1988, Khoury wrote, composed, and produced all of the songs himself. Khoury started a new phase in his life in 1989, not as a singer but as a keyboard player and a band conductor, and appeared on TV. He continued as a keyboard player until 1996, and played with many Lebanese artists. But during that period, Khoury wrote and sang the single, "Fik Yamma Balak". It was released in 1994 and established him as a singer. In 1997, he wrote, composed and performed his second single "Lasbor Ala Welah". It was not until 1999 that Khoury finally became known in the music industry as a writer/composer when he released two songs for Nawal Al Zoghbi, "Tia" and "Dalouna". In 2001, Khoury launched his first official album, Khayal El-Omer, and the next year, Khoury shot his first video clip "Ya Shog". Khoury has twice been awarded the Murex d'Or. He first won in 2003 and, in 2004, he was awarded the Murex d'Or for Best Multi-Talented Artist. In 2005, Khoury signed a five-year contract with the Rotana Records. He also released his next album, Kil Al Asayed. The album and the title song were well received. It was this album that made Khoury famous in the Arab World. In 2006, Khoury released an additional album Asr El Sho. His album Ana Wl Leil was released on March 2008; on this album, the lyrics for the track "Lawla L Hawa" were written by the famous Emirati poet, Jenan. Khoury's last album with Rotana, Rajain, contained 10 tracks and was released in 2010. In January 2011, Khoury announced that his contract with Rotana had ended and that he would be moving to self-production. Khoury has performed live at the Cairo Opera House and the Carthage Film Festival of Tunisia
Personal life
Marwan is single. Rumors linked him with singer Carole Samaha after the success of their duet, "Ya Rab", but they denied the rumors.