The two curlers released a statement on Wednesday night, saying Morris was leaving Martin's rink, which includes second Marc Kennedy and lead Ben Hebert.
"Unfortunately we have had a challenging past few seasons and have not lived up to our expectations of being the best curling team in the world," said Morris.
After forming prior to the 2006-07 season, the foursome was one of the most dominant in the curling’s history, capturing the Tim Hortons Brier in 2008 at Winnipeg and 2009 at Calgary, both with undefeated records.
The Martin rink also won the world men’s championship in 2008 at Grand Forks, N.D., and finished second a year later at the World Men’s Championship in Moncton, N.B.
The team also won a gold medal for Canada at the 2010 Winter Olympics in Vancouver.
"As much as we've all tried very hard to find a way to fight back and get better, in the end it was obvious that we needed a change," said Morris. "Myself and Kevin were no longer thriving in our back-end role like we did in our 2010 Olympic gold-medal run. I have always been a very driven and intense athlete and right now, in this situation, I feel my passion and love for the game of curling is not where it needs to be. As a result, it is with a very heavy heart that I will be stepping down as my role of third on Team Martin."
"It is never an easy thing to have a team member decide to leave your team,” said Martin. “John Morris was an integral part of what made Team Martin the best team in curling for many years and Olympic gold medallists (in 2010). But change is unfortunately inevitable."
Morris's departure does not affect Martin's direct-entry berth for the Tim Hortons Roar of the Rings Canadian Curling Trials, Dec. 1-8 in Winnipeg.
A replacement player for Morris will be announced at a later date.