Chadwick, who had his original loan spell cut short by injury, will act as backup to The Lions' current strike force in the run-in to the end of the season. Thanks to the successful FA Cup campaign, Dennis Wise's men face a heavy schedule as they bid to make the play-offs, with games coming thick and fast.
Despite signing until the end of the season, Chadwick will not be eligible for the FA Cup Final, should Millwall overcome Sunderland on April 4th.