The series stars Jason Isaacs as Michael Britten, a cop who lives in two worlds - one in which his wife died in a car crash and another in which his son was killed.
Alias actor Weisman will play 'Mr. Blonde', a mysterious figure who appears in both worlds and holds vital information regarding the accident, according to Entertainment Weekly.
Since Alias concluded in 2006, Weisman has appeared in episodes of Chuck, Fringe and CSI.
Awake has not yet been given a premiere date by NBC. The series temporarily shut down production in late 2011, with executive producer Howard Gordon claiming that the show's writers needed additional time to work on the complex scripts.
Gordon recently insisted that Awake will not confuse viewers, suggesting that it has "a fairly gettable concept".
"[Britten] sees clues and details that cross over from one world to the next, and he uses that insight to solve crimes," he explained. "Whatever learning curve there might be, we hope it's a shallow one."
The Event's Laura Innes and former Law & Order: SVU star BD Wong are among the other actors who have signed up to appear on the show.
> Awake Jason Isaacs: 'US TV is a cutthroat business'
> Jason Isaacs: 'Awake is a high-concept risk'
Watch a trailer for Awake below: