| Year | Title | Role | Notes | Ref. |
| 2015 | Locke & Key | Tyler (voice) | Audio drama | |
| 2013 | Teacher's Lounge | Matt | | |
| 2017–2020 | CollegeHumor Originals | Various | | |
| 2017 | Fallen For You | Todd | Pilot released on YouTube | |
| 2018–present | Dimension 20 | Dungeon Master, various | Also creator, executive producer | |
| 2018 | Liverspots and Astronots | Lancery (voice), various | | |
| 2019–present | Adventuring Academy | Himself | | |
| 2019–present | Game Changer | Himself | Also executive producer |
| 2019–2022 | Mission to Zyxx | Kor Balevore (voice) | 318: "Malice in Chains" 501: "O Others, Who Art Thou?!" 503: "Good Spot Hunting" 505: "Being Jawn Malevolent" 507: "A Little Ditty 'Bout Jakk and Shai'An" 512: "A Noob Hope" 515: "Gary's Home Companion" 520: "The Whole Mufalata" 521: "The Ass End" | |
| 2019 | The Adventure Zone: The Dadlands | Game Master | | |
| Ultramechatron Team Go! | Galatax | | |
| 2020 | Rude Tales of Magic | Kreedis (voice) | Episode: "Mountaintop" | |
| 2021 | Hello from the Magic Tavern | Kalhaxorus the Grim (voice) | Season 3 Episode 77: "Death Knight" Season 4 Episode 87: "Death Knight Visits" Season 5 Episode 52: "Prison Kalhaxorous" | |
| by Night | Adrian Clairmont | Episode: "Live on the Moon" Episode: "Reign in Hell" | |
| Battle for Beyond | Nikhil | | |
| 2022–present | Make Some Noise | Himself | Also executive producer |
| 2022 | Legends of the Multiverse | Dungeon Master | | |
| Roll20 10 year Anniversary stream | Citizen Doctor Abraham Mehermblur | 3 episodes; "D&D Strixhaven", "D&D Chaos", "D&D Chaos 3" | |
| Exandria Unlimited: Calamity | Dungeon Master | 4 episodes | |
| 2022–present | Critical Role | Brigidda (one-shots) | Episode: "Elden Ring One-Shot: O Ye of Little Faith" | |
| Dungeon Master (campaign 3) | Episode: "The Nox Engine" Episodes: "Downfall Parts 1–3" | |
| Dungeon Master (campaign 4) | Main cast | |
| 2023–present | Worlds Beyond Number (The Wizard, the Witch, and the Wild One) | Dungeon Master | Creator-owned podcast | |
| 2023 | Candela Obscura (The Circle of Needle & Thread) | Sean Finnerty | 3 episodes | |
| 2024 | Bigger! With Brennan and Izzy | Himself | Improv special | |
| The Adventure Zone: Abnimals | Sgt. Salamander | Podcast; Episode: "Bunny Heist!" | |
| 99% Invisible | Himself | Podcast; Episode: "Brennan Lee Mulligan" | |
| 2024–2025 | Very Important People | Augbert, Greg Excitement | 2 episodes | |
| 2025 | Exandria Unlimited: Divergence | Dungeon Master | 4 episodes | |
| Wildemount Wildlings | Padmund Pondhop | 3 episodes | |
