The lower house Wednesday approved the revised deal between the government and the Revolutionary Armed Forces of Colombia, or FARC. The vote was 130-0 and came after about 11 hours of debate.
The rebels have 150 days to put down their arms, according to the legislation.
Last week marked the second time this year that Colombian President Juan Manuel Santos and FARC leader Rodrigo Londoño have signed a peace deal aimed at ending Latin America's longest war.
In October, Colombian voters rejected the first version of the agreement
in a national referendum, sending negotiators back to the table.
This time, the revised peace agreement went to Congress for approval.
Santos was awarded the Nobel Peace Prize this year for "his resolute efforts" to end the civil war, which is the longest running conflict in the region.
Some critics have said the changes to the peace agreement are merely cosmetic, but key players supported the agreement.
Todd Howland, Representative of the UN High Commissioner for Human Rights in Colombia, voiced concerns about what he and his teams were already seeing following the negotiations.
"These empty lots left by the FARC are supposedly to be filled by the State, working to transform the illicit economy to licit," he said, referencing land the group had occupied. "This is not happening right now. Instead, other illegal groups are entering into these areas." During the last two months, he said his field teams have encountered FARC soldiers asking what is going to happen to them, saying some members are already being offered work with criminal groups.
Half a century of conflict
The battle between FARC and the country's government has been devastating. It began in 1964, after the success of the Cuban revolution, with rebels wanting to forcibly redistribute wealth.
In the more than five decades since it started, the armed group has seized territory, attacked government forces and interfered with political life through high-profile kidnappings. As decades passed, thousands of people were killed.
Up to 220,000 died in the insurgency and as many as 5 million people were displaced -- more than one out of every 10 Colombians.
Funded by a sophisticated cocaine trafficking network and armed with child soldiers, the rallying cries to protect an agrarian society had begun to sound antiquated and obsolete.
"Guerrilla war is no longer seen as a reasonable way to contest power," Cynthia Arnson, director of the Latin America Program at the Woodrow Wilson International Center for Scholars, had previously told CNN.