David Klemmer says he is leaving and joining Newcastle for family, not financial, reasons.
The Knights have signed Klemmer on a five-year deal.
The NSW and Kangaroos front-rower requested a release from the Bulldogs and has joined Newcastle on a deal worth around $4.3 million.
The Roosters have released Dylan Napa from his contract so he can sign with the Dogs and replace him.
Klemmer told NRL.com he is moving north because of his family.
"I'm not going for money," he said. "People think they know what happens in people's lives but I'm not selfish. I am taking my family to an environment that I think they need.
"I am putting what I believe is my family's best interests ahead of everything else. If people think that's selfish then I can live with it.
"I don't feel the need to justify it. It's my own business. What I will say is that I think Newcastle, not just as a club but as a city, will make me a better person.
"And I hope I can contribute to helping make Newcastle a better football team in return."