His film roles include co-starring opposite Jodie Foster in Robert Zemeckis's Contact as Willie, a fellow scientist with an affinity for brightly colored shirts, and sharing the screen with Tom Hanks and Matt Damon in Saving Private Ryan as Corporal Henderson, ranking NCO of Pfc.

In 2013, Guillermo del Toro cast Martini and Rob Kazinsky as the Australian father-son pilot duo in Pacific Rim.

[7] Martini's television credits include a lead role in the Sci-fi Channel's Emmy nominated mini-series Taken and appearances as Agent Steve Goodrich on the second season of 24.

He was also cast in X-Files creator Chris Carter's Harsh Realm, and had a recurring role in the Canadian series Da Vinci's Inquest.

After memorable guest-star turns in popular series, including Numb3rs, Walker Texas Ranger, CSI: Crime Scene Investigation and CSI: Miami, Martini landed a lead role in The Unit, a series about a tier-1 US Army special operations team created by David Mamet and produced by Shawn Ryan of The Shield.

Martini remains active in the theater, having co-founded the Theatre North Collaborative in New York City, a company of American and Canadian actors dedicated solely to producing new works from both sides of the border.

In 2015, Martini starred as the title character in Amazon Studios' Western series Edge, written and directed by Shane Black.