The UN Office on Drugs and Crime (UNODC) said the acreage under coca cultivation rose to 171,000 hectares in 2017, a 17% increase from 2016.
The agency warned production could harm recent peace-building efforts.
Colombia is the world's largest producer of cocaine, much of which ends up in the US - which is the world's largest consumer.
Gloria María Borrero Restrepo, Colombia's justice minister, reportedly called the data "really very worrying".
The country has fought for years against cocaine production, with the US sending around $400m (£304m) each year to aid their war.
According to the UNODC report, the coca production acreage in Colombia last year was the highest ever recorded level, increasing by 25,000 hectares from 2016.
Eighty per cent of the coca has been grown in the same area for the past 10 years, while crops produce 33% more coca leaf - the main cocaine ingredient - than they did in 2012.
Newly-elected President Ivan Duque told reporters the government would create a new drug-fighting policy, saying the goal was to have "concrete results" in the next four years.
A scheme to use drones to spray coca crops with herbicide has, however, attracted criticism.
Mr Duque's predecessor, Juan Manuel Santos, suspended aerial fumigation using the chemical glyphosate in 2015, following warnings by the World Health Organization (WHO) that the chemical could be linked to cancer.
The country's cocaine trade is still flourishing despite the 2016 peace deal in Colombia, which ended five decades of armed conflict with major rebel group the Farc.
Some blame the government for concentrating too hard on peace, while others said that by going clean the Farc rebels left a vacuum in the trade they once controlled.