The one-month truce for the end-of-year holiday season lasted from December 15 to midnight last day.
"The final moment of the unilateral ceasefire has arrived" said Pablo Catabumbo, one of the guerrilla delegates in peace talks with the Colombian government in Havana.
"Some sources have been speculating that the FARC had decided to prolong the ceasefire until elections," which will be held in March for the legislature and May for the presidency, Catabumbo said, but he said that was not the case.
The government of President Juan Manuel Santos said that during previous attempts at negotiating peace, the FARC used bilateral ceasefires to reinforce its military.