"We certainly wish him and his family all the best for the future."
Mateo, who turns 31 on May 2 next year, was in the Warriors' grand final side in his first season with the club in 2011.
Moving to Auckland after 88 appearances for Parramatta since his first-grade debut in 2004, he finishes five games short of 100 appearances for the Warriors. In his 95 games he scored 44 points from 10 tries and two goals.
While naming Mateo as a new signing, Manly also confirmed stalwart Anthony Watmough's release from the club.
Manly chairman Scott Penn revealed the three big name squad changes when the club also unveiled highly-rated former South Sydney and Chelsea FC administrator Joe Kelly as their new chief executive.
The shake-up up comes following Monday's sacking of general manager David Perry as part of an ownership restructure.
Penn also dismissed talk that coach Geoff Toovey was under pressure to retain his job and said that club captain Jamie Lyon would see out his distinguished career at the Sea Eagles.
Penn added that he was "very confident" that New Zealand international Steve Matai, who earlier this year sought a release from the club during a season of off-field bickering, would soon also sign a contract extension.
Matai is currently committed until the end of 2015 and Toovey is hopeful the classy centre will remain long-term.
- With AAP