The businessman and lawyer, whose ventures include a clothing line, wine and rum brands, and a restaurant, earned US President Donald Trump's endorsement despite never having run for office.
De la Espriella defeated Iván Cepeda by one percentage point, or more than 251,000 votes.
The result effectively was an indictment of outgoing President Gustavo Petro's government, whose policies Cepeda had promised to continue, including a largely failed effort to establish dialogue with multiple armed groups.
Electoral authorities published all but a fraction of the vote count hours after polls closed on Sunday. Petro and Cepeda did not accept those results, with the latter saying he would wait for a recount to do so. Authorities finished the recount before declaring de la Espriella's victory.
De la Espriella's victory adds Colombia to a growing list of countries that have turned to political outsiders in search for solutions to complex social, security and economic challenges.
The self-proclaimed representative of "the never-before-seen" promised voters fearful of renewed internal conflict to take a heavy-handed approach to combating violent crime with strategies borrowed from Salvadoran President Nayib Bukele's playbook, including building mega-prisons.
Cepeda conceded Colombia's presidential election to de la Espriella and accepted a Senate seat reserved for the runner-up in the presidential election.
"We assume with serenity, responsibility and absolute resolve - and let there be no doubt about it - the role that circumstances demand of us," Cepeda said in an address to the nation.
"We will exercise a democratic, vigilant and constructive opposition."
De la Espriella, 47, will begin a four-year term on August 7.
In a statement, his campaign said the president-elect's "purpose is to work for national unity, with the people and for the people."
The campaign also stated his government will be committed to guaranteeing "the right to political opposition and peaceful protest, within the framework of the constitution, the law and respect for democratic institutions."
More than 26 million people voted in the polarising runoff, setting a historic record. Of those, over 426,000 people chose a third, no-name option on the ballot that allows voters to express dislike of both candidates. About 29,000 people cast blank ballots.
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