| Year | Title | Role | Notes | Ref. |
| 1999, 2008 | Law & Order | Mike | Episode: "Patsy" | |
| Jay Carlin | Episode: "Submission" | |
| 2002 | Law & Order: Special Victims Unit | Terry Jessup | Episode: "Dolls" | |
| 2003 | Hack | Christopher Clark | Episode: "Presumed Guilty" | |
| 2004, 2009 | Law & Order: Criminal Intent | Wesley John Kenderson | Episode: "Silver Lining" | |
| Paul Devildis | Episode: "Family Values" | |
| 2007 | The Unit | Gary Weber | Episode: "Five Brothers" | |
| 2009 | Lie to Me | Frank Ambrose | Episode: "The Better Half" | |
| Royal Pains | Dan Samuels | Episode: "It's Like Jamais Vu All Over Again" | |
| 2011–2012 | Pan Am | Roger Anderson | 6 episodes | |
| 2012 | Midnight Sun | Ethan Davies | Unsold NBC TV pilot | |
| Blue | Cooper | 3 episodes | |
| 2012–2014 | The Newsroom | Elliot Hirsch | 10 episodes | |
| 2013 | Elementary | Dr. Mason Baldwin | Episode: "Lesser Evils" | |
| 2014 | Rake | David Potter | 11 episodes | |
| Manhattan | Dr. Reed Akley | 10 episodes | |
| 2014–2015 | State of Affairs | David Patrick | Main role; 13 episodes | |
| 2015–2016 | Banshee | Robert Dalton | 2 episodes | |
| 2016 | Crisis in Six Scenes | Vic | Episode: | |
| 2016–2025 | Stranger Things | Jim Hopper | Main role; 42 episodes | |
| 2018 | Drunk History | Vietnam Memorial Head | Episode: "Underdogs" | |
| Animals | Hawk | Voice, episode: "Roachella" | |
| 2019 | El Hormiguero 3 | Himself (guest) | Episode: "David Harbour" | |
| Saturday Night Live | Himself (host) | Episode: "David Harbour/Camila Cabello" | |
| 2020 | The Simpsons | Fred Kranepool | Voice, episode: "Undercover Burns" | |
| 2021 | Big City Greens | Rick | Voice, episode: "The Van" | |
| Q-Force | Agent Rick Buck | Voice | |
| Star Wars: Visions | Tajin | Voice, episode: "The Elder"; english dub | |
| Marvel Studios: Assembled | Himself | Episode: "The Making of Black Widow " | |
| 2024–present | Creature Commandos | Eric Frankenstein | Voice; main role | |
| 2024 | What If...? | Alexei Shostakov / Red Guardian | Voice; 2 episodes | |
| 2025 | The Rookie | Security Guard | Uncredited, episode: "Out of Pocket" | |
| Marvel Zombies | Alexei Shostakov / Red Guardian | Voice; 3 episodes | |
| 2026 | DTF St. Louis | Floyd Smernitch | Main role; 7 episodes | |
