Marsh was elevated to the Colts' 53-man roster from the team's practice squad Thursday.
Heading into a Thursday night matchup against the Titans, Indianapolis has elected to bolster its linebacking corps with the addition of Marsh. The 28-year-old has made four appearances this season, all for division-rival Jacksonville, but he now prepares for his Colts debut after joining the team's practice squad Oct. 24. Marsh has suited up for 88 career games in the NFL, compiling a total of 168 tackles and 14 sacks.