Marco Vallisa was kidnapped on July 5 along with two other workers from Macedonia and Bosnia in the town of Zuwara. The two others were freed several days later.
A foreign ministry statement said Vallisa was on his way back to Italy but gave no details of how he was freed.
Libya has seen a rise in kidnappings of diplomats, foreigners and Libyans, with a fractious government and parliament unable to control militias that helped oust Muammar Gaddafi in 2011.
Vallisa worked for the northern Italian construction company Piacentini Costruzioni, Reuters reported.