Listed at five-foot-nine-inches and 210 pounds, Butler spent last season on the Oakland Raiders’ practice squad.
Butler spent his final year of college with the University of Iowa Hawkeyes after transferring from the University of Nevada.
The 24-year-old had 91 rushes for 396 yards with a touchdown for the Hawkeyes.
In his time in Nevada, the Bloomingdale, Ill. native was named an All-Mountain West honourable mention in 2015 and 2016.
He also earned his team’s outstanding offensive player award in 2016.
Throughout his college career, Butler rushed 699 times for 3,712 yards with 28 touchdowns.
He also had 53 receptions for 485 yards with three touchdowns.
The news came on the same day the Riders announced the addition of Special Teams Coach Terry Eisler who spent the past four years with the University of Alberta Golden Bears in the same role.
Last week, the Riders signed star linebacker Solomon Elimimian to a one-year deal. Elimimian spent his entire career with the B.C. Lions and was named most outstanding defensive player in 2014 and 2016.
The 32-year-old is the Lions all-time leader in defensive tackles with 745. He was also part of the Lions 2011 Grey Cup championship.