He is best known for his roles in various films, including American Psycho (2000), You Can Count on Me (2000), The Deep End (2001), A Beautiful Mind (2001), Sweet Home Alabama (2002), Wonderland (2003), Hulk (2003), Secondhand Lions (2003), An Unfinished Life (2005), Stealth (2005), Glory Road (2006), Poseidon (2006), Life as We Know It (2010), The Lincoln Lawyer (2011), Red Dog (2011), J. Edgar (2011), The Mend (2014), Breakthrough (2019), Ford v Ferrari (2019), The Secret: Dare to Dream (2020), The Forever Purge (2021) and The Black Demon (2023).

He appeared as a guest star on several TV sitcoms in his early 20s, including Fox's True Colors and Parker Lewis Can't Lose, the family drama Life Goes On, and CBS's private-eye show Jake and the Fatman.

Lucas followed this appearance by working with executive producer Steven Spielberg and then-unknown actor Clive Owen in the TV-movie Class of '61, which follows the stories of a group of West Point cadets in 1861 as the Civil War breaks out.

He took his first stab at comedy in The Definite Maybe, in which he played a recent college graduate who gets fired from his job and schemes with an old friend to purchase a house in the Hamptons.

He also appeared in an off-Broadway production of Terrence McNally's controversial Corpus Christi, a retelling of the Passion, with the Jesus character (named Joshua) and his disciples all being gay.

[4] Following a series of operations to reset his nose, he began gathering larger roles in films like American Psycho, The Weight of Water, Session 9, The Dancer, When Strangers Appear, and You Can Count on Me.

One of Lucas' first feature roles was playing Jace "Flash" Dillon in the cinematic PC flight simulator Wing Commander III: Heart of the Tiger.

Lucas gained mainstream exposure after his roles in Sweet Home Alabama, A Beautiful Mind, and as Glenn Talbot in Hulk.

Lucas' other documentary work includes Operational Homecoming, Trumbo, and the Los Angeles Film Festival Audience Award-winning Resolved.

In February 2010, he was cast in the Anders Anderson thriller Stolen the single father of a mentally challenged boy, starring alongside Rhona Mitra and Jon Hamm; the film had a limited theatrical release in March 2010.

In 2011, Lucas co-starred with Rachael Taylor in the film Red Dog, based on the true story of an Australian Kelpie.

The directorial debut of John Magary premiered at South By Southwest in March 2014 with Lucas receiving a series of positive reviews for his portrayal of Mat, one of two dysfunctional brothers who collide in a small Harlem apartment.

'"[21] Lucas supported President Barack Obama during the 2008 presidential campaign, volunteering to help potential voters register at colleges in Pennsylvania.