"He brings speed, leadership and experience into our young group and will be a major help to our developing younger players.
"Dallin has some wonderful attributes, has a well-rounded game and is a great competitor. We look forward to him joining us for the back end of this season and three more seasons after that."
With a total of 143 appearances for Penrith and Canterbury Bankstown, Watene-Zelezniak will link up with the Warriors in Terrigal on the Central Coast for the rest of the 2021 campaign.
He's also set to line up against his old club when he makes his first Warriors appearance at Mount Smart Stadium in their 22nd-round match against the Bulldogs on August 15.
"It's fantastic being able to bring the New Zealand captain into our squad," said Warriors CEO Cameron George.
"He's a highly respected leader on and off the field and will be a major asset to our club and to the community."
In his nine appearances for the Bulldogs this year, Watene-Zelezniak averaged a career-best 167 metres a game, scored five tries and made 34 tackle breaks.
"Signing Dallin happened really quickly," said Warriors recruitment manager Peter O'Sullivan.
"He now has stability at our club and can settle into one position and enjoy his footy. It's a great result to have a senior player and the New Zealand captain with us."
Bulldogs boss Aaron Warburton thanked Watene-Zelezniak for all his efforts while at the club.
"Dallin has put in a massive effort while here at the Bulldogs and I know that everyone at the club would like to thank him for what he has given during his time at Belmore.
"He has now received an opportunity to join the Warriors and we can appreciate what that means to him as a proud New Zealander.
"We wish him and his family all the best with the move and for the future."
After scoring two tries in his NRL debut in 2014, Watene-Zelezniak played his first test for the Kiwis in 2016.
He captained his country for the first time against the Kangaroos in a famous win at Mount Smart Stadium in 2018 and then in three tests against England.
He was again captain for the mid-year test against Mate Ma'a Tonga in 2019 but was ruled out of the end-of-season tests against Australia and Great Britain.