The 57-year-old actor, whose film credits include Spiderman 2 and An Education, will take on the role of Deputy District Attorney Morales in the latest edition of the long-running crime drama franchise.
The show's creator, Dick Wolf, released a statement on Saturday saying that he was "thrilled" to have Molina join the new spin-off.
The only other confirmed cast member thus far is former Jericho actor Skeet Ulrich, who will take on the role of Detective Rex Winters. A number of high-profile stars, including Lucy Liu and Michael Rapaport, are also reportedly being considered for roles.
Law & Order: Los Angeles will premiere this fall on NBC.