Freeman signed a one-year contract with the Cowboys on Tuesday, Todd Archer of ESPN.com reports.
Freeman rushed four times for two yards and caught his lone target for 13 yards during Sunday's 21-20 victory against San Francisco.
Freeman rushed six times for 16 yards during Sunday's 28-20 victory against the Commanders.
Freeman rushed three times for nine yards during Sunday's 37-31 overtime loss to the Ravens.
Freeman gained zero yards on his only rushing attempt during Sunday's 36-19 victory against the Browns.
Freeman will serve as the Rams' No. 2 running back Sunday against the Cardinals with Los Angeles set to activate Kyren Williams (ankle) from injured reserve ahead of the Week 12 contest, Jourdan Rodrigue of The Athletic reports.
Freeman rushed 12 times for 32 yards in Sunday's 20-3 loss to the Packers.
Freeman is the Rams' likely starting running back for Sunday's game against the Steelers, and he and Darrell Henderson are expected to take on "the majority of the workload" out of the backfield, a source tells Adam Schefter of ESPN.
The Rams signed Freeman off their practice squad Tuesday.
The Rams elevated Freeman to their active roster Saturday.