Morley will return for the 27 June Test against NZ at St Helens

Morley, 29, joined the Roosters from Leeds in 2001 but rejected a two-year contract extension to stay in Sydney.

"I've decided to join Warrington because the club is really moving in the right direction," he said.

"I want to win a championship and I see Warrington as the place to do it. They are very ambitious."

Morley, who was initially offered a one-year extension in Sydney, decided to move back to the northern hemisphere for job security.

Wigan have got a few problems at the moment and I thought Warrington were the much better option Adrian Morley

"It came down to the longevity of the contract rather than the money at this stage of my career," Morley told reporters at the Halliwell Jones Stadium via a telephone link-up from Sydney.

"The Roosters couldn't match the four-year deal offered by Warrington.

"But I've got a good relationship with the club and they wished me well."

Salford-born Morley said he considered approaches from the Reds and Leeds and rejected Wigan because of their position at the foot of the Super League table.

"I was talking to Salford and Leeds because of my ties with both cities but, once I heard what Warrington had to say, I was very excited," he said.

"Wigan also showed an interest. I have a good working relationship with [coach] Brian Noble and it was tempting to team up with him again.

I put Adrian Morley in a similar bracket to Andrew Johns Wolves coach Paul Cullen

"But Wigan have got a few problems at the moment and I thought Warrington were the much better option."

Warrington coach Paul Cullen said: "This announcement that we have signed Adrian Morley on a four-year contract is one that should excite everyone connected with the club.

"We should celebrate the fact that we have signed a unique player, a born leader, the type of player who inspires others, the type of player we want.

"He leads from the front and is battle hardened after playing in the toughest competition in the sport.

"He will bring a massive go-forward to our pack, setting an example with his ability and professionalism which will rub off on everyone and in particular some of our younger players.

"I put Adrian Morley in a similar bracket to Andrew Johns. Of course as Great Britain prop forward he is a totally different type of player to Johns, but is in a similar category because of his character and ability."

Morley, who is flying to England for the Test against New Zealand on 27 June, could also play for Warrington before the end of the season if the Roosters fail to make the NRL play-offs in Australia.

"We want to make the play-offs with the Roosters but, if it gets to the stage where we are definitely out of contention, we'll assess it then," he said.

"There would be eight or nine weeks before the international series starts which is a long time without any football."

Morley also revealed that he still aims to be available for the end-of-season Tri-Nations series in Australia in November despite needing an operation on snapped ligaments in his wrist.

"My wrist does need corrective surgery," he said.

"The operation is probably a 10-week recovery period so I'll hopefully have it done straight after the Tests and still be back for the start of the Super League season."