The 31-year-old former All Black made his Munster debut against Edinburgh in September 2012 and in his first season he featured in 27 of Munster's 30 games. He won his 37th cap against Perpignan on Saturday.
Commenting on the news, Laulala said: "I have loved my time with Munster and there's a lot of rugby still to be played. I want to achieve success with these guys and hope to continue to contribute in any way I can."
Munster head coach Rob Penney added: "We understand Casey's reasons for leaving at the end of the season and are disappointed to see him go.
"I'm sure he will continue to commit himself to the goals we set out at the beginning of the season and will contribute to Munster's campaign."