President Ivan Duque announced in a statement that Euclides Espana -- alias Jhonier -- had been "neutralized."
"This is one of the greatest blows that has been dealt the FARC dissidents. And we are talking about a criminal with more than 25 years of murderous and criminal record," the president said in a public statement.
"FARC" refers to the Revolutionary Armed Forces of Colombia, which until 2016 had waged more than half a century of armed conflict against the state.
That year they signed a pact to end the fighting -- but dissident members of the group have splintered off.
Jhonier, whose age has not been revealed, coordinated several of the dissident organizations that are commanded by Gentil Duarte and Ivan Mordisco, two of Colombia's most wanted men.
He was listed as a terrorist by the United States and the Colombian government had offered $755,000 for information leading to his arrest.
Short and stocky, Jhonier was unknown to the public until he gave an interview in 2020 about the splinter group's expansion that was published in the newspaper El Espectador.
A photograph of the dissident leader showed him dressed in camouflage and carrying a rifle. He described himself as a member of "the true armed resistance that did not go to Havana," the site of the peace process that led to demobilization of some 13,000 men and women.
Jhonier fell in an action by military troops with the support of the police in the municipality of Tacueyo, in the department of Cauca, the military said.
"We used state-of-the-art technology for intelligence (...) and our best troops so that they could advance mainly at night and that is how today, around 3:00 in the afternoon, this symbol of evil was neutralized," said General Luis Fernando Navarro, commander of Colombia's armed forces.