"To play for the biggest club in the world with such a history meant a lot to me," Blind, capped 54 times by the Netherlands, wrote on Twitter.
"I want to thank everyone, the managers, coaches, the medical department, everyone who helped me to settle in so quick at the beginning, of course my team mates and last but definitely not least the fans."
The 28-year-old, who came through the Ajax academy and played over 100 senior matches for the club, arrived at United in 2014 but was not a first-team regular under manager Jose Mourinho.
Able to play in midfield or defence, Blind won the FA Cup with United in 2016, and the League Cup and Europa League titles the following year.
Blind made 90 Premier League appearances in four years at Old Trafford but was limited to only seven last season.
(Reporting by Hardik Vyas in Bengaluru, editing by Ed Osmond)
