His third stint with the team was a short one. Boreham had just signed on to the Riders' practice roster last week.
The Vancouver native spent three seasons with the club and helped Saskatchewan win a Grey Cup in 2007.
Boreham, who was drafted by the B.C. Lions in 2001, also played for the Toronto Argonauts and Winnipeg Blue Bombers.
Also Thursday, the Roughriders signed running back Stephfon Green to the practice roster and released linebacker Aaron Crawford, offensive lineman John Hashem and linebacker Brian Peters.