The polling stations began to close at 11 p.m. local time in Sweden, and vote counting began.
Above all, the race concerns three candidates.
Leftist Senator Iván Cepeda has narrowly led in opinion polls ahead of the election. He is allied with outgoing President Gustavo Petro and has pledged to continue his efforts to achieve peace with the country's remaining guerrilla and rebel groups.
Opposing Cepeda are the right-wing candidates, lawyer Abelardo de la Espriella and conservative senator Paloma Valencia.
Both have promised a tougher, more aggressive line against rebels, drug cartels and other criminals. They are both outspoken supporters of US President Donald Trump.
In many ways, the election is a vote on Petro's peace policy, which has failed to tame, among other things, the groups that refused to lay down their arms in connection with the peace agreement with the FARC guerrillas in 2016.
On the contrary, critics and experts believe that criminals and guerrillas have exploited the power vacuum and peace attempts to advance their positions. Recent years have been marked by car bombs, political assassinations, extortion and rampant drug trafficking.
At the same time, Petro's four years in power have, for example, increased employment and raised minimum wages - a direction that Cepeda intends to continue.
If no candidate receives at least 50 percent of the vote - which is likely - the top two will face off in a second round on June 21.
