Hull FC have beaten off competition from a number of other Super League clubs to sign Great Britain and England forward Gareth Ellis.
Ellis, 30, has agreed to join the Black and Whites in November on a three-year deal from Australian side Wests Tigers.
The former Leeds Rhinos man announced in February that he would be returning to England for family reasons.
"He's possibly the biggest signing the club has ever made," director of rugby Shaun McRae told BBC Radio Humberside.
"I'm delighted to say we've got his signature on a three-year contract.
"It's a clear sign of intent as to what this club wants to do and where we want to be."
"I still really want to win things and achieve things," said Ellis. "And I really believe I can do that at Hull FC.
"I was lucky to have a few clubs interested, but I've been listening to Hull and to the ambition they have got and the prospects they're trying to put in place for the future.
"And the bottom line for me was that it was a great time to be involved with Hull FC.
Leeds, St Helens and Huddersfield were all strongly linked with Ellis, who said only last year that he would eventually like to end his career back with boyhood heroes Castleford.
But, aside from any financial incentives offered by ambitious Hull, one factor for Ellis was that he has already worked with the Black and Whites' new coach Peter Gentle at Wests Tigers.
"I did a lot of research into the club and speaking to the likes of Peter, Adam Pearson and Shaun McRae, I really started to share their enthusiasm and I believe the club can be anything it wants to be.
"I said originally that I would maybe like to return to one of my old clubs or my home-town club Castleford but when I looked at it and thought about it more, I realised I still really wanted to win things and achieve things and I really believe I can do that at Hull FC."
Gentle added: "If we're looking to take this club to another level, we need the addition of one or two class players to bring out the best of the talented squad we currently have in place. We have definitely achieved that with the signing of Gareth.
"It's not only about what he brings to the team on the pitch, but having a world class player interacting with our young squad members will have a significant influence on their development and will enhance the culture we have at this club."