The seven-year veteran was a fifth round pick in the 2005 NFL Draft. He played his first two seasons for the Detroit Lions before joining the Houston Texans in 2010 and the Indianapolis Colts in 2011. Orlovsky, 33, played two seasons for the Tampa Bay Buccaneers before reuniting with the Lions last season.
The University of Connecticut product has 12 career starts and owns a 75.3 quarterback rating. For his career, Orlovsky has completed 58.2 percent of his passes for 3,132 yards, 15 touchdowns and 13 interceptions.
He hasn't taken a regular season snap since 2015. Rams quarterback coach Greg Olson was Orlovsky's offensive coordinator and quarterback coach in 2005 with the Lions.
In February, he posted a Twitter message indicating his departure from Detroit.
"Detroit Vs Everybody," he posted. "It'll always be where it started for me. It'll always have a piece of my heart."
In May, Orlovsky told the Hartford Courant that he was deciding between multiple offers about where to sign.
"I've played for a dozen years and it's been amazing," Orlovsky told the Courant. "I've played with guys who are some of the best in the history of the game. I've played in blowouts on the good side, I've played in blowouts on the bad side. I've played at every stadium in the NFL. I've played Monday Night Football, Sunday Night Football. I've been part of a lot of cool stuff. I haven't bought sneakers in 16 years and I haven't bought Gatorade since I was 10. It's been awesome."
Orlovsky's wife posted a message to her Instagram account on Thursday.
"Well for his 13th year @dorlovsky is heading to the LA Rams!!! We couldn't be more excited and proud! But holy cow he's leaving next week already.... #footballisbackfortheorlovskys #larams #nfl #hardestworkeriknow#hesstillgotit #13thyear," Tina Orlovsky wrote.
The post featured the couple's children yelling: "Let's Go Rams."
Orlovsky comes in at No. 3 on the Rams' depth chart behind Jared Goff and Sean Mannion. Rams quarterbacks posted a 69.5 quarterback rating last season.