Simon was signed to the Titans' active roster Tuesday, Jim Wyatt of the team's official site reports.
The 31-year-old was cut by the Titans on Nov. 6 but will now return to the team. In one game for the team this season, he made three tackles while playing 19 snaps on defense. With David Long (hamstring) and Rashaan Evans (ankle) both questionable for Week 12 against the Patriots, Simon may be asked to step right into a substantial role this weekend.