The deal puts a definitive end to fighting in Latin America's longest civil war, which has torn the country apart with shootings and bombardments in its coca-rich jungles and hills.
President Juan Manuel Santos and FARC leader Timoleon Jimenez shook hands and smiled after negotiators signed the deal at a ceremony in Cuba.
The deal establishes "a bilateral ceasefire and end to hostilities and the definitive laying down of arms," according to the text.
"This is a historic day for our country," Santos said in a speech to assembled leaders including UN Secretary General Ban Ki-moon.
"After more than 50 years of confrontations, deaths, attacks and pain, we have put a final end to the armed conflict with the FARC."
Disarmament will begin after the signing of a full final peace agreement, expected within weeks.
Colombian President Juan Manuel Santos, left, Cuba's President Raul Castro, center, and Commander of the FARC, Timoleon Jimenez pose at the signing ceremony. Source: AAP
Thursday's agreements "leave us on the verge of completing a final accord relatively soon," Jimenez said.
The final deal "will allow us to return at last to legal political activity through peaceful and democratic means," he added.
Tears of joy
In the Colombian capital Bogota, crowds gathered to watch the announcement on a big screen.
One man, Camilo Gonzalez, was moved to tears.
"It has been a tragic journey. Millions of victims, people displaced, fighting, broken dreams," he said.
"But I think now we have reached a moment of hope."
Under the agreement, the Revolutionary Armed Forces of Colombia (FARC) must hand over its weapons to United Nations monitors within six months.
The announcement of the deal was an emotional moment for many in the country. Source: AAP
The FARC's members -- an estimated 7,000 or so -- will gather in "normalization zones" for a demobilization process.
The sides also agreed to government action against "criminal organizations" blamed for fueling the conflict.
The United States congratulated Colombia. "We will stand ready to help the Colombian people as they work toward a just and lasting peace," said US National Security Advisor Susan Rice.
The European Union's foreign representative Federica Mogherini in a statement called it a "a turning point in the Colombian peace process."
"Now all efforts must be devoted to reaching a final comprehensive agreement that will pave the way to durable peace in the country" and justice for victims, she said.
260,000 dead
The Colombian conflict started in the 1960s as a rural uprising for land rights that spawned the communist FARC.
The conflict has drawn in various leftist rebel groups, right-wing paramilitaries and drug gangs over the decades.
It has left 260,000 people dead, 45,000 missing and nearly seven million displaced, according to official figures.
Human rights groups say atrocities have been committed on all sides. Many families are still searching for missing loved ones.
Thursday's deal resolves one of the final points in peace talks between the government and the FARC, the country's largest rebel group.
However, the means of implementing the final peace deal remain to be settled after three-and-a-half years of negotiations.
The two sides said they would wait for the courts to rule on whether a referendum can be held to endorse the accord, and would accept the court's decision.
Although peace with the FARC would virtually end the conflict, other armed groups are still operating in Colombia.
A bid to hold peace talks between the government and the second-biggest rebel group, the leftist National Liberation Army (ELN), has stumbled because of its alleged kidnappings.
"The activity of the ELN above all and the criminal gangs means that we cannot yet talk of a complete end to the armed conflict," said Kyle Johnson, Colombia analyst for the International Crisis Group.
"It will be the end of Colombia's biggest armed conflict, but not all of them."
Timeline of Colombia's rebel conflict
Here are key dates in Latin America's longest armed conflict, which has killed 260,000 people according to official data.
1964: FARC formed
The government launches an offensive against communist groups in the center and west of the country. On May 27, rebel commander Manuel Marulanda Velez flees the government assault with 47 other men and forms the FARC.
1984: First peace bid
On March 28, conservative president Belisario Betancur launches peace talks with the FARC under a bilateral truce.
The initiative breaks down in 1987 after right-wing paramilitaries assassinate a presidential candidate from a party allied to the FARC. Further peace efforts collapse in 1992 and 2002.
1996: Hostages taken
On August 30 the FARC takes 60 Colombian soldiers hostage at a military base in the south.
The raid marks the start of its strategy of mass hostage-takings that dominates the conflict over the following years.
2000: 'Plan Colombia'
In June the United States and Colombian president Andres Pastrana launch "Plan Colombia," a joint anti-narcotics strategy.
It is later broadened to include anti-guerrilla operations. Washington has spent more than $8.0 billion on the effort.
2002: Betancourt captured
In February the FARC kidnap Ingrid Betancourt, a Franco-Colombian politician. During six years' captivity in the jungle she becomes an international symbol of the conflict. She is rescued by the military in 2008.
2011: FARC leader killed
The FARC's top commander Alfonso Cano is killed in a raid by the Colombian army on November 4. He is replaced by current leader Timoleon Jimenez.
Two other top leaders of the force, Raul Reyes and Jorge Briceno, were killed in 2008 and 2010.
2012: New peace talks
On October 4, President Juan Manuel Santos's government launches the latest peace talks with the FARC, weakened by the loss of its top leaders.
2016: Full ceasefire
On June 22 The FARC and government say they have agreed on a definitive ceasefire. Santos says he hopes to seal a full peace deal by July 20.
