FitzGerald, 22, had three assists and 134 penalty minutes while splitting 39 games between Peoria of the American Hockey League and Alaska of the ECHL.
Guenette, 23, had 13 goals and 42 assists in 67 games with Victoria of the ECHL.
The Canucks also re-signed forward Jozef Balej on Wednesday. Terms of the deal were not released.
Balej, 25, scored 13 goals and added 17 assists in 39 games last season with FC Fribourg-Gotteron of the Swiss League.