Seda’s film debut was in the boxing film Gladiator (1992), in which he played the role of Romano, a Cuban boxer. He has since worked in various films and TV series. In 1995, Seda was nominated Best Male Lead at the Spirit Awards for his role in the movie I Like It Like That (1994), opposite Rita Moreno and Lauren Vélez. In 1996, he was nominated for the Palme d’Or (Best Actor Award) at the Cannes Film Festival, for his role as Blue in the film The Sunchaser, opposite actor Woody Harrelson.

Also in 1997, Seda landed the role of Detective Paul Falsone on NBC’s: Homicide: Life on the Street. The writers, taking advantage of his boxing background, wrote a shirtless practice bout into an episode, which established his character’s attractiveness to fellow detective Laura Ballard. Seda also boxed opposite Jimmy Smits in the film Price of Glory (2000).

Seda married his long time girlfriend, Lisa Gomez, in 2000. The couple have four children.

Seda has appeared in more than two dozen movies, including Bad Boys II (2003) as Roberto, as well as numerous television appearances. Aside from Homicide, he has had notable roles as Dino Ortolani in Oz, Matty Caffey in Third Watch, Paul Falsone (in a Homicide crossover with Law & Order), House, and CSI: Miami. He is featured as one of the three leads in the HBO World War II mini-series The Pacific (released on March 14, 2010), portraying Marine John Basilone. Seda appeared as a guest star in an episode of Burn Notice, and in 2007 he made a cameo appearance in Ludacris’ song “Runaway Love”, as an abusive, alcoholic stepfather.

In 2012, Seda began portraying Detective Antonio Dawson in Dick Wolf’s Chicago franchise, first starring in Chicago Fire in a recurring role and then, in 2014, as part of the main cast of the spin-off Chicago P.D. In 2017, Seda carried his role over into another spin-off, Chicago Justice, which was canceled after its first season. His daughter Haley made a guest appearance on Chicago P.D. as a key witness in a bombing. In July 2017, it was announced that Seda would return to Chicago P.D. following the cancellation of Chicago Justice. On April 19, 2019, it was reported that NBC/Wolf Entertainment officials informed Seda that they would not be renewing his contract, which led to his leaving the series shortly after six seasons.

Seda appeared in Treme seasons 2-4 as Nelson Hidalgo, a politically connected land developer from Dallas who helps out with the relief efforts in post-Katrina New Orleans. He appeared in the film Larry Crowne (2011), which starred and was co-written and directed by Tom Hanks. Hanks also served as an executive producer on The Pacific, in which Seda starred. In 2013, Seda starred alongside Sylvester Stallone, Christian Slater, and Jason Momoa in the Walter Hill-directed action thriller Bullet to the Head.

In 2020, Seda will play the lead role of Dr. Benjamine Glass in the NBC apocalyptic drama pilot La Brea which was written by David Appelbaum.