The 32-year-old has agreed a two-year deal with the O’s and becomes their fifth summer arrival following the expiration of his contract at Sky Bet League One side Yeovil Town.
Born in Tonypandy, Wales, Lawless started his career at Ton Pentre before making the switch to England in 2003 to sign for Fulham following a successful trial.
Capped by Wales at youth level, the midfielder was unable to make the breakthrough at Craven Cottage, and following two years with the Cottagers signed for Torquay United.
Lawless would go on to spend a year with the Gulls, before agreeing to sign for Forest Green Rovers in August 2006.
The move proved to be a huge opportunity for the midfielder, as he went on to become an integral part of the side and he racked up a total of 120 appearances during his three years at The New Lawn.
The summer of 2009 then saw the midfielder on the move once again, as he penned a deal at York City having turned down several Football League sides.
Following a successful first season with the Minstermen which consisted of forty-five appearances, Lawless attracted the interest of Luton Town and in November 2010 made the switch to Kenilworth Road on an initial loan deal which was made permanent in January 2011.
Lawless went on to spend over five years with the Hatters, helping the club achieve promotion back to the Football League at the end of the 2013/14 season, and made a total of 203 appearances before departing in 2016.
July 2016 then saw the midfielder agree a one-year deal with Yeovil and during his season at Huish Park, made a total of thirty-nine appearances for the Glovers.