The new season of the sitcom is set to premiere July 18.
The therapist role was recently left vacant with the unexpected death of actor Stanley Kamel last month. Kamel played Monk's beloved therapist, Dr. Charles Kroger.
The announcement regarding the decision to fill Kamel's position was made Wednesday by Jeff Wachtel, USA's executive vice president of original programming.
"Monk will always need a therapist -- and it's a part that is pivotal to the central themes of the show. When we lost Stanley, we knew we needed an actor who could bring warmth, intelligence and humor to the role," Wachtel said in a statement. "Hector was actually the first person that came to mind, and we are incredibly fortunate that he's agreed to do some episodes with us. Stanley can never be replaced, but we think he'd be very pleased with our choice."