Lemon shared team lead in sacks with six for the Edmonton Eskimos last season. The six-foot-one, 245-pound import DL added 16 tackles, two pass knockdowns, two fumble recoveries and one forced fumble in 11 starts.
Calgary also signed import quarterback Jimmy Coy.
Coy was the National Association of Intercollegiate Athletics player of the year after a standout career at Saint Xavier University. The 6-0, 210-pound pivot ranked third in the United States with 3,427 passing yards last season despite missing two games with an injury.
Coy also led the Cougars to a national title in 2011.
Meanwhile, Calgary released import defensive lineman Kevin Dixon after he failed to pass his physical. The Stamps also placed import QB Ryan Perrilloux, who has passport issues, on the suspended list.