allen was signed to the chicago bears practice squad on september 5, 2011. he was promoted to the active roster on december 19 after safety chris conte was placed on injured reserve. with the injuries to matt forté and marion barber, allen made his debut on christmas day against the green bay packers and rushed for 40 yards on 11 carries. allen lost the third running back battle to lorenzo booker, and was waived on august 31, 2012. he was later placed on the team's practice squad, but was added to the active roster after booker was put on injured reserve on september 8.