The 57-year-old actor joins previously announced star Skeet Ulrich on the upcoming spin-off, set to debut this fall on NBC.
"I am thrilled that Fred is 'LOLA''s Deputy D.A.," creator and executive producer Dick Wolf said in a statement to Deadline, which first reported the news. "He joins a remarkable list of some of America's greatest character actors like Sam Waterson, Vincent D'Onofrio, Jeff Goldblum, Steven Hill, Dianne Wiest and Michael Moriarity as stars of the Law & Order-branded series."
Morales is described as a narcissistic but self-deprecating and altruistic prosecutor, according to casting breakdowns. Coming from a political family, he hopes to serve in public office one day.
Molina is best known for his role as Doctor Octopus in Spider-Man 2 and most recently starred in the 2009 Oscar-nominated film An Education. He also previously appeared on both Law & Order: SVU and Law & Order: Trial By Jury in a crossover between the two series in 2005.
Law & Order: Los Angeles is scheduled to air on Wednesdays at 10/9c on NBC.