Ocampo, 69, who has a Phd in economics from Yale University, is an experienced public servant who previously served as Colombia's minister of finance in the government of former President Ernesto Samper, and has held numerous positions in the United Nations.

He is currently a professor at Columbia University in the United States.

"Jose Antonio Ocampo will be our finance minister (to) build a productive economy and an economy for life," Petro said in a message on Twitter alongside a photo of the two men standing side by side.

The election of Petro, a former M-19 guerrilla, marks a radical change for a country still scarred by decades of conflict. Nearly half of Colombians live in poverty, and many voters are frustrated with the right-leaning political establishment.

The President-elect has promised to tackle deep inequality with pension redistributions, free university education and other social programs.

Last week Petro named long-time politician and peace envoy Alvaro Leyva as his minister of foreign affairs.