The 30-year-old goalkeeper signed a four-year deal.
The Netherlands goalkeeper made 32 appearances in three seasons at the Nou Camp.
Cillessen won two La Liga titles, two Copa del Rey titles and the Spanish Super Cup.
However, the La Liga champions, Barcelona released a statement wishes Cillessen the best of luck and success in the future.
The statement reads:
Barcelona would like to publicly express its gratitude to Jasper Cillessen for his commitment and dedication, and wishes him the best of luck and success in the future.
Cillessen joined Barcelona from Ajax in the summer of 2016 for £11.1m.