The veteran linebacker signed with the Hamilton Tiger-Cats on Wednesday, a day after being released by the Toronto Argonauts.
The signing of Isaac also comes a day after Hamilton released veteran linebacker Markeith Knowlton, the CFL's outstanding defensive player in 2010.
Hamilton also signed defensive back Emanuel Davis while releasing receiver Ouslet Volcy.
Isaac had 16 tackles and one sack this season with Toronto after helping the Argos win the 100th Grey Cup last November.
Davis attended Hamilton's training camp after previously spending time with the NFL's Cleveland Browns.