The talks are the latest in a long history of attempts to end the conflict which has left tens of thousands dead since the establishment of the Revolutionary Armed Forces of Colombia, or FARC, in 1964.
Colombian President Juan Manuel Santos is betting that a decade of U.S.-backed blows against the FARC has battered the group to the point where it will seriously seek to end the war.
"The peace process will be successful if it's serious, realistic and efficient," chief Colombian negotiator Humberto de la Calle said in Hurdal, Norway.
"The process that starts today is different from the past."
The two sides appeared at joint table separated in the middle by representatives of Cuba and Norway. It is the first time that the rebels and government have met publicly since failed negotiations from 1999 to 2002.
The FARC and government delegations agreed to start discussions in Havana, Cuba on November 15, according to the joint declaration, which was read by a Cuban representative.
Although ten years of strikes against the FARC have cut their ranks by more than half and put their leadership on the run, defeating the rebels with military means alone has proved difficult, leaving a negotiated deal as the best alternative.
"We've come to look for peace with social justice in Colombia," Ivan Marquez, head of the FARC delegation and member of the group's ruling seven-member secretariat, said.