He was the leader of an offshoot of the Armenian Secret Army for the Liberation of Armenia (ASALA) in the 1980s and the most celebrated commander during the Nagorno-Karabakh War in the early 1990s.

An Armenian-American, Melkonian left the United States and arrived in Iran in 1978 during the beginning of the 1979 Revolution, taking part in demonstrations against the Shah. Following the collapse of the Shah's monarchy, he traveled to Lebanon during the height of the civil war and served in an Armenian militia group in the Beirut suburb of Bourj Hammoud. In ASALA, he took part in the assassinations of several Turkish diplomats in Europe during the early to mid-1980s. He planned the 1981 Turkish consulate attack in Paris. He was later arrested and sent to prison in France. In 1989, he was released and in the following year, acquired a visa to travel to Armenia.

Melkonian had no prior service record in any country's army before being placed in command of an estimated 4,000 men in the Nagorno-Karabakh War. He had largely built his military experience beginning from the late 1970s and 1980s, when he fought in Lebanon with ASALA. Melkonian fought against various factions in the Lebanese Civil War and against the IDF in the 1982 war.

Melkonian carried several aliases over his career and was known as Avo to the troops under his command in Nagorno-Karabakh. The last years of his life were spent fighting with the Nagorno-Karabakh Defense Army.Monte was killed by Azerbaijani soldiers while surveying Merzili with five of his comrades in the aftermath of battle.He was buried at Yerablur cemetery in Yerevan and declared a National Hero of Armenia in 1996.

Melkonian was born on November 25, 1957 at Visalia Municipal Hospital in Visalia, California to Charles (1918−2006) and Zabel Melkonian (1920−2012). He was the third of four children born to a self-employed cabinetmaker and an elementary-school teacher. By all accounts, Melkonian was described as an all-American child who joined the Boy Scouts and was a pitcher in Little League baseball. Melkonian's parents rarely talked about their Armenian heritage with their children, often referring to the place of their ancestors as the "Old Country." His interest in his background only sparked at the age of eleven, when his family went on a year-long trip to Europe in 1969.

While taking Spanish language courses in Spain, his teacher had posed him the question of where he was from. Dissatisfied with Melkonian's answer of "California", the teacher rephrased the question by asking "where did your ancestors come from?" His brother Markar Melkonian remarked that "her image of us was not at all like our image of ourselves. She did not view us as the Americans we had always assumed we were." From this moment on, for days and months to come, Markar continues, "Monte pondered [their teacher Señorita] Blanca's question Where are you from?"

In the spring of that year, the family also traveled across Turkey to visit the town of Merzifon, where Melkonian's maternal grandparents were from. Merzifon's population at the time was 23,475 but was almost completely devoid of its once 17,000-strong Armenian population that was wiped out during the Armenian Genocide in 1915. They did find one Armenian family of the three that was living in the town, however, Melkonian soon learned that the only reason this was so, was because the head of the family in 1915 had exchanged the safety of his family in return for identifying all the Armenians in the town to Turkish authorities during the genocide.^[13] Monte would later confide to his wife that "he was never the same after that visit....He saw the place that had been lost."

Monte was killed in the abandoned village of Merzili in the early afternoon of June 12, 1993 during the Battle of Aghdam. According to Markar Melkonian, Monte's older brother and author of his biography, Monte died in the waning hours of the evening by enemy fire during an unexpected skirmish that broke out with several Azerbaijani soldiers who had likely gotten lost.

Monte was buried with full military honors on June 19, 1993 at Yerablur military cemetery in the outskirts of Yerevan, where his coffin was brought from the Surb Zoravar Church in the city center. Some 50,000 to 100,000 people (some reports put the figure as high as 250,000), including Armenian President Levon Ter-Petrosyan, acting Defense Minister Vazgen Manukyan, Deputy Foreign Minister Gerard Libaridian, government officials, and parliamentarians attended his funeral.

The Karabakh town of Martuni was renamed Monteaberd (or Monteapert; Armenian: Մոնթեաբերդ; literally "Fort Monte").

In 1993 the Monte Melkonian Military Academy was established in Yerevan.