Maitland began his career with Canterbury in New Zealand, where he was born, before moving to Crusaders and then on to Glasgow Warriors in 2012.
He made his international debut the following year and joined London Irish in 2015.
Moving across the capital to Saracens the following year, he has played 147 games during his time in north London.
He scored in the 2018-19 Premiership final win against Exeter Chiefs as Saracens won a league and Champions Cup double.
Maitland also helped them win the Championship in 2020-21 after the club was relegated due to breaching salary cap rules.
He represented Scotland in the 2015 and 2019 World Cups and on the 2013 British and Irish Lions tour of Australia.
Saracens’ director of rugby, Mark McCall, said: “We feel very fortunate to have shared the last eight years with Sean.
“He has been an outstanding competitor on the field and a brilliant team mate off it.
“Sean is loyal, humble, fun and in his own quiet way has played a key role in driving the values we hold dear. He is respected by everyone and will be greatly missed by us all.”