| Year | Title | Role | Notes |
| 1999 | Any Day Now | Clerk | Episode: "A Parent's Job" |
| 1999–2000 | Angel | Lucas, Mars | 2 episodes |
| 2000 | Brutally Normal | Lenny | 2 episodes |
| The Michael Richards Show | Dennis | Episode: "Simplification" |
| 2000–2007 | Gilmore Girls | Kirk Gleason, Mick | 137 episodesSeries regular |
| 2001 | Inside Schwartz | Focus Group Guy | Episode: "Bless Me Father, for I Have Fired You" |
| DAG | Ryan | Episode: "Prom" |
| 3rd Rock from the Sun | Attendant | Episode: "You Don't Know Dick" |
| Going to California | Joey "Fuzz" Fucetti | 4 episodes |
| 2002 | Yes, Dear | David Scott | Episode: "Making Baby" |
| 2002–2003 | Andy Richter Controls the Universe | Phil | 3 episodes |
| 2004 | Gilmore Girls Backstage Special | Himself | Television film |
| 2007–2008 | October Road | Vincent "Rooster" Road | 6 episodes |
| 2008 | Scream Queens | Himself | 1 episode |
| Sparky & Mikaela | Dude | Episode: "Pilot" |
| Humanzee! | Humanzee | Episode: "Pilot" |
| 2008–2009 | James Gunn's PG Porn | Peppermint Patty, Jason, Bill Scrotey | 8 episodesAlso co-creator and writer |
| 2009 | True Jackson, VP | Justin | Episode: "ReTRUEnion" |
| The Jace Hall Show | Himself | Episode: "James Gunn & Brutal Legend" |
| 2011 | For a Green Card | Andrew | Episode: "What Could Possibly Go Wrong?" |
| 2012 | Antiques Roadshow | Himself | Episode: "Junk in the Trunk 2" |
| Glee | Phineas Hayes | Episode: "Makeover" |
| 2012–2013 | H+ | Jason O'Brien | 9 episodes |
| Bunheads | Sebastian | 2 episodes |
| 2013 | The Education of Eddie and Mortimer | Creepy Carl | Television film |
| 2014 | The Victoria Uyen Show | Himself | Episode: "Guardians of the Galaxy Premiere" |
| Bones | Dr. Howard Fitch | Episode: "The Corpse at the Convention" |
| 2016 | Superstore | Card Shopper | Episode: "Secret Shopper" |
| Gilmore Girls: A Year in the Life | Kirk Gleason | Miniseries |
| 2018 | Robot Chicken | Various Voices | Episode: "Why Is It Wet?" |
| 2021 | What If...? | Kraglin Obfonteri | Voice, episode: "What If... T'Challa Became a Star-Lord?" |
| The Rookie | Treasure Hunter | Episode: "Poetic Justice" |
| 2022 | The Terminal List | Saul Agnon | 1 episode |
| The Guardians of the Galaxy Holiday Special | Kraglin Obfonteri | Also motion-capture performance for Rocket |
| 2023 | The Good Doctor | Kenny | Episode: "Love's Labor" |
| The Marvelous Mrs. Maisel | Stewart Jones | Episode: "The Testi-Roastia" |
| Marvel Studios: Assembled | Himself | Episode: "The Making of Guardians of the Galaxy Vol. 3 " |
| 2024–present | Creature Commandos | Weasel, G.I. Robot | Voice |
| 2025 | Celebrity Jeopardy! | Himself (Contestant) | |
| Peacemaker | Maxwell Lord | Episode: "The Ties That Grind" |
