The handover of Lopez was the third such hostage release by the rebel group this week.
The rebels had already freed four members of the armed forces and Alan Jara, a former governor, earlier this week.
Lopez, 45, was snatched along with 11 other provincial politicians during a daring raid by rebels posing as soldiers and police who were searching for a bomb in Cali city centre.
Rebels bundled the kidnap victims onto a bus and took them into the mountains.
Al Jazeera's Mariana Sanchez in Colombia said Lopez later told a crowd in Cali that Farc had executed other politicians held as hostages by the group during a raid on a Farc camp.
Lopez survived as Farc rebels were holding him in another camp at the time.
The group has said that the politicians were killed in a crossfire during the raid.
Piedad Cordoba, a Colombian senator who helped broker the releases and accompanied the mission, said she had brought back a communique from Alfonso Cano, the Farc's top commander, but said she would provide details later.
Lopez was the last politician the group was holding and the releases have raised speculation that the Farc's is seeking to gain political ground after a string of military setbacks in their four-decade war.
The Farc, which has waged a decades-long war against the Colombian government, once controlled large areas of Colombia, but has been battered by a US-backed security campaign under Alvaro Uribe, the Colombian president.
In addition, three of its top commanders died last year and the group's numbers have fallen sharply due to desertions sparked by low morale.