Cox sacked Toronto quarterback Zach Collaros for a seven-yard loss on the Argos' second offensive play to record his 111th tackle of the season. The previous club record of 110 was set in 1996 by Tracy Gravely.
It was also Cox's 11th sack of the season, tying him with teammate John Bowman.
Cox finished with five tackles on the night, upping his season total to 115. He also notched another sack to make it an even dozen.
The CFL record for tackles is 130 in 2012 by Edmonton's J.C. Sherritt, who was named the CFL's top defensive player that year. The 30-year-old Cox came into the Toronto game leading the league in tackles this season.
Cox, an undersized linebacker at five foot nine and 185 pounds, is an eight-year veteran from Columbus. Ohio. In 2012, he led the team with four interceptions and a career-high 82 tackles.
He started his career as a defensive back.