| Year | Title | Role | Notes |
| 2005 | Coke | Gonzales | TV short |
| The Colbert Report | Spencer | Episode: "Greg Behrendt" |
| 2007 | Fat Guy Stuck in Internet | Co-Worker, Linux, The Oracle | 3 episodes |
| Honesty | Mechanic | Episode: "Mechanic" |
| 2008 | Human Giant | Kidnapped Soldier, Rapzilla, Billy Crystal | 2 episodes |
| 2009 | Californication | Annoying Hipster | Episode: "Mia Culpa" |
| 2010 | Comedy Lab | Ruby | Voice, episode: "Penelope Princess of Pets" |
| This Show Will Get You High | Cast Member | Comedy Central pilot |
| Nick Swardson's Pretend Time | Various | Episode: "Mudslide Junction" |
| 2010–2011 | Funny or Die Presents | Nick, Performer | 3 episodes |
| The Back Room | Mr. America, James Gandolfini | 4 episodes |
| 2010–2012 | The Life & Times of Tim | Co-Worker, Walker Fan, Adam's Friend, Doug the Intruder | Voice, 4 episodes |
| 2011 | Happy Endings | Carl | Episode: "Your Couples Friends & Neighbors" |
| Curb Your Enthusiasm | Pig Parker | Episode: "Vow of Silence" |
| Bored to Death | Faux Jonathan | Episode: "We Could Sing a Duet" |
| 2011–2013 | The League | Gavin | 2 episodes |
| 2011–2014 | Eagleheart | Brett Mobley | Series regular; 26 episodes |
| 2012 | The Office | The Magician | Episode: "Welcome Party" |
| The Inbetweeners | Mr Gilbert | Recurring; 7 episodes |
| Aqua Teen Hunger Force | Rocket Horse | Voice, episode: "Rocket Horse & Jet Chicken" |
| 2012–2013 | Go On | Mr. K | Series regular; 22 episodes |
| 2012–2015 | Comedy Bang! Bang! | Dog Lawyer, Mr. Celebrity | 2 episodes |
| 2013 | Ghost Ghirls | Rabbit | Episode: "I Believe in Mira-ghouls" |
| NTSF:SD:SUV:: | Gabby Hofstein | Episode: "Unfrozen Agent Man" |
| We Are Men | Alimony Steve | Episode: "We Are Franksgiving" |
| 2013–2014 | Drunk History | Various | 2 episodes |
| 2013–2015 | Kroll Show | Various | 3 episodes |
| 2014 | Surviving Jack | Principal McMullen | Episode: "Rhythm Is a Dancer" |
| Adventure Time | Ring Master | Voice, episode: "Sad Face" |
| Bad Teacher | Doug Pilaf | 5 episodes |
| Dinner with Friends with Brett Gelman and Friends | Himself | Special |
| 2014–2015 | Married | A.J. | Series regular; 23 episodes |
| 2014–2016 | Mr. Pickles | Cheeseman | Voice, 2 episodes |
| TripTank | Jeff | Voice, 9 episodes |
| 2015 | Dinner with Family with Brett Gelman and Brett Gelman's Family | Himself | Special |
| Fresh Off the Boat | Dusty Nugget | Episode: "Persistent Romeo" |
| Man Seeking Woman | Demon | Episode: "Stain" |
| The Odd Couple | Stuart | Episode: "Jealous Island" |
| Mad Men | Daniel | Episode: "Person to Person" |
| 2015–2016 | Blunt Talk | Ronnie | 6 episodes |
| 2015–2018 | Another Period | Hamish Crassus | Recurring; 20 episodes |
| 2016 | Angel from Hell | Lee | 2 episodes |
| Clarence | Mr. Mozer | Voice, episode: "Field Trippin |
| Dinner in America with Brett Gelman | Himself | Special |
| High Maintenance | Himself | Episode: "Selfie" |
| 2016–2018 | Love | Dr. Greg Colter | Recurring; 10 episodes |
| 2016–2020 | American Dad! | Various voices | 6 episodes |
| 2016–2019 | Fleabag | Martin | Series regular; 7 episodes |
| 2017 | Jeff & Some Aliens | Jeff | Voice, main role (10 episodes) |