Coulson, 28, has joined the O’s initially until January 2018, and arrives in E10 following 10 years at the Abbey Stadium.
Handed his Cambridge United debut in October 2007 as a substitute in a 2-2 home draw with Halifax Town, Coulson went on to make a total of 17 appearances during his first season in senior football.
Once established within the U’s first team, Coulson registered his first senior goal in March 2010, scoring in a 3-1 win at home to Salisbury.
The central defender then went from strength to strength at Cambridge, becoming a consistent figure in the back four and helping the Amber Army achieve promotion from the Conference at the end of the 2013-14 season.
With the U’s promoted, Coulson continued to feature regularly and marking his first appearance in the Football League with the winning goal in a 1-0 opening day victory at home to Plymouth Argyle.
With over 300 appearances to his name for the U’s, the central defender was rewarded for his service to the Club with a testimonial against Tottenham U23s this summer.
Coulson will be at tomorrow’s pre-season friendly at Billericay Town where O’s fans will get a chance to see the defender in action for the first time.