"It has been my honour to serve the people of Saanich North and the Islands for the past 16 years," he said in a written release.
"I will be leaving this post with a deep appreciation of the strength and vibrancy of the communities that make up this riding, and the generosity and involvement of its citizens."
Coell says his retirement has nothing to do with the Liberals' low standing in the polls.
"I'm strictly looking at years of elected service and my age, and it's time to make room for a younger energetic person on the peninsula here," he said.
Coell served as the mayor of Saanich for six years before being elected to the B.C. legislature in 1996. He was re-elected in 2001, 2005, and 2009.
Coell says he plans to spend more time with family and friends, but will work with Premier Christy Clark to ensure the riding remains in Liberal hands in the election next May.
“I will look back on my career with pride and satisfaction, knowing that my public service has been personally fulfilling and worthwhile," he said.
On Monday, Surrey-Tynehead MLA Dave Hayer announced he would not seek re-election after 11 years in public office.
Fellow Liberal MLAs Kevin Krueger and Kash Heed recently announced they, too, would not be running again.
There's also been speculation about the intentions of some of Clark's key cabinet ministers, including Finance Minister Kevin Falcon and Education Minister George Abbott.