Acquired from the Super Bowl champion New England Patriots for a pair of draft picks, Glenn is being counted on as Brett Favre's main target this season.
But as in New England, the oft-injured Glenn has been hampered by a bad knee and missed the Packers' first three exhibition contests.
Glenn started in this one and had an uneventful debut as he finished with two catches for 33 yards while playing the first half.
Favre saw limited action in the first quarter, going five of 10 for 57 yards.
Craig Nall, who is battling for a roster spot, threw touchdown passes of 16 and 25 yards in the fourth quarter to Charles Lee, giving the Packers a 21-14 lead.
The Titans had a chance to send the game into overtime when Billy Volek threw a 13-yard touchdown pass to Eddie Berlin with eight seconds remaining. But Tennessee went for the win and on the conversion attempt, Volek's pass hit Berlin in the shoulder and fell incomplete, allowing the Packers to escape.
Ryan Longwell kicked a pair of field goals for the Packers (3-1), who open the regular season at home against Atlanta.
The Titans (2-2) host the Philadelphia Eagles in their opener.