| Year | Title | Role | Notes |
| 1995 | Saturday Night Live | David Duchovny's son | Episode: "David Duchovny/Rod Stewart" |
| New York News | | Episode: "Welcome Back Cotter" |
| 1997 | Stranger in My Home | Drew | TV movie |
| Cybill | Timmy | Episode: "The Wedding" |
| 1998 | Another World | Steven Frame | Temporary: February 25 and 27, 1998 |
| Grace and Glorie | Bicycle Kid | TV movie |
| The Pretender | Patrick Harper | Episode: "Stolen" |
| 1999 | As the World Turns | Matthew John "M.J." Dixon | |
| Seven Days | Evan Hamilton | Episode: "For the Children" |
| 2000–2001 | Cover Me | Chance Arno | Main cast, 24 episodes |
| 2001 | Say Uncle | Nick | TV movie |
| 2001–2006, 2017 | Will & Grace | Elliot | Regular season 4; recurring seasons 3, 5–6, 8; special guest season 9 (14 episodes) |
| 2003 | Maniac Magee | Jeffrey Lionel Magee | TV movie |
| My Life with Men | Ben | TV pilot |
| ER | Zack | Episode: "The Greater Good" |
| 2004 | Less than Perfect | George Denton | Episodes: "The Crush", "Claude's 15 Minutes of Christmas" |
| 2005 | Summerland | Jeb Ekhart | Episodes: "Leaving Playa Linda", "Where There's a Will There's a Wave" |
| Kevin Hill | Ethan Claypool | Episode: "Only Sixteen" |
| 2007 | 24 | Scott Wallace | 4 episodes |
| 2012 | Entry Level | Jake | TV movie |
| 2014–2015 | The Knick | Dr. Bertie Chickering, Jr. | Main cast |
| 2014 | Drunk History | Walt Disney | Episode: "Hollywood" |
| 2017–2018 | I'm Dying Up Here | Eddie Zeidel | Main cast |
| Mom | Cooper | Episodes: "A Seafaring Ancestor and a Bloomin' Onion", "A Bear and a Bladder Infection" |
| 2018–2021 | This Is Us | Nick Pearson | Recurring role, 7 episodes |
| 2019 | Dollface | Steve | Episode: "Beauty Queen" |
| 2020 | PEN15 | Greg | Episodes: "Play" and "Opening Night" |
| A Teacher | Tinder Date | Episode 9 |
| 2022 | Minx | Glenn | Main role (season 1) |
| Angelyne | Danny | Episodes: "Glow in the Dark Queen of the Universe" and "Pink Clouds" |
| 2024 | Laid | Richie | Main role |
| 2025 | Devil in Disguise: John Wayne Gacy | Sam Amirante | Main role |
| TBA | Margo's Got Money Troubles | Mark | Upcoming miniseries |
