The move was made Wednesday morning after the team also announced running back Chris Douglas had been waived/injured. Douglas, also an undrafted rookie, was hurt in practice Tuesday.
Brown is listed at 5-foot-10 and 220 pounds. He completed his college career at Pittsburgh last season, and had 357 yards rushing and five touchdowns in 11 games. He spent the 2007-2010 seasons at Wisconsin, where he had 1,152 yards rushing and 11 touchdowns in 36 games.
The Bills were familiar with Brown after the player took part in the team's rookie minicamp in May on a tryout basis.