USC's previously announced 2016 opener will be against Alabama at AT&T Stadium in Arlington, Texas.
The games against Western Michigan and Las Vegas will be season openers.
USC defeated Utah State, 17-14, in 2013 at the Coliseum to improve to 5-0 against the Aggies. In 1997, the Trojans defeated Las Vegas, 35-21, at the Coliseum.
USC has never played Western Michigan.
Western Michigan's website reported that the 2017 game against the Trojans was initiated by former Western Michigan football player Alec Gores, a Beverly Hills resident and businessman. Over dinner with USC President Max Nikias and Athletic Director Pat Haden, Gores discussed his desire to see Western Michigan play the Trojans, the website said.
Gores has a net worth of $2.1 billion, according to Forbes.com.
Western Michigan Athletic Director Kathy Beauregard and Haden signed the contract for the game in Gores' home, the website said.