Moch spent last season with the Tennessee Titans, where he played in three games and had four tackles. He also spent time with the Arizona Cardinals and Cincinnati Bengals. The Bengals drafted Moch in the third round of the 2011 NFL draft.
Defensive backs Brandon Underwood and Matt McGarva along with wide receiver Aaron Kelly also signed with Toronto.
Kelly played with the Winnipeg Blue Bombers last season while also suiting up for the Hamilton Tiger-Cats for two years. Over his career, he has caught 103 passes for 1,360 yards and six touchdowns. Last season with Winnipeg, he had a career-high 43 receptions for 549 receiving yards and three touchdowns.
It is Underwood's second stint with Toronto after spending part of last season on the Calgary Stampeders practice roster. Underwood started seven times in 2014 with the Argos, collecting 19 defensive tackles, one special teams tackle, two interceptions and one fumble recovery.
McGarva, a native of Surrey, B.C., spent the last two years with the BC Lions. The University of Windsor alumni recorded five special teams tackles with the Lions.
The Argonauts also added DL Cleyon Laing and offensive lineman Branndon Braxton to the suspended list.