Chalk it up as a depth move for an 8-6 team that also lost Michael Bush on Tuesday, placing the running back on season-ending injured reserve with the rib injury that slowed him to a crawl in recent weeks.
Bell, cut loose by the New York Jets this month to make room for receiver Braylon Edwards, was previously released by the Bears in October. Bell spent the past two seasons in Chicago and remains familiar enough with the offense to slip into a backfield that ranks 12th in the league in rushing.
The battered status of Chicago's backfield increases the pressure on Matt Forte. He ran for 60 yards on 20 carries against the Green Bay Packers on Sunday and should see plenty of work this weekend against the Arizona Cardinals.
Armando Allen also saw two carries against the Packers, but the loss of Bush is a problem for the Bears. He served as the team's goal-line rusher all season, a role we saw Forte struggle with against the Packers.
Follow Marc Sessler on Twitter @MarcSesslerNFL.