Jagodowski began improvising in the early 90s. He started out on several Harold teams at iO Chicago. In 1998, he was cast in the Mainstage cast of The Second City, where he appeared in revues on both Mainstage and e.t.c. stages alongside Kevin Dorff, Susan Messing, Stephnie Weir, and many others. Since 2002, he has been performing at iO with David Pasquesi in the long-running improv show "TJ & Dave."

Since 2004 T. J. has starred as one half of the "Two Guys" for the Sonic Drive-In commercials alongside fellow improviser Peter Grosz.

The Chicago Improv Festival called Jagodowski "The best improviser in Chicago". New City Chicago said, "If Miles Davis had pursued comedy instead of music, the results might have looked something like this." Jagodowski performs weekly in Chicago in a variety of improv programs, but most notably in "T. J. and Dave" with David Pasquesi, which the Chicago Reader has described as "an hour of subtle character development, Verbal facility, and pantomimic agility that anticipates and plays off the audience's reactions." Since 2006, the duo performs this show monthly at The Barrow Street Theatre in New York City, and have been performing the show weekly since 2002 in Chicago.

The 2009 South by Southwest Film festival included the documentary "Trust Us, This is All Made Up" directed by Alex Karpovsky, which chronicles a "T. J. and Dave" performance.

Jagodowski was a guest on the NPR program Wait Wait... Don't Tell Me! on the weekend of November 2–3, 2013.