O'Byrne was a regular for the Coatbridge club after joining from Dumbarton in 2009.
Livi chief executive Ged Nixon said that signing the player was a "good piece of business" for last season's Third Division champions.
"Finding a big and strong centre back was one of our main targets for the close season and we're very happy that Michael has agreed to join us," he told the club's official website.
"We're aware that he had other offers - including at least one from a First Division club - so it's great to get him on board for the challenges ahead."
Source: BBC Sport
Source: BBC Sport