Roosters winger Blake Ferguson.

Parramatta have poached in-demand Roosters winger Blake Ferguson on a three-year deal starting in 2019, with Eels coach Brad Arthur confident he can keep the former NSW Origin flyer on the straight and narrow.

Ferguson rejected another three-year offer - from Newcastle - as well as an extension to remain at Bondi, to link with the Eels next season and remain close to his two young children in Sydney.

Ferguson told his Roosters teammates on Wednesday of his intention to depart for Parramatta with the Eels announcing the deal later that night.

The 28-year-old has been in terrific form for the Roosters this year, repeatedly crediting his turnaround to cleaning up his act off the field, having given up alcohol since the start of the season and also checking himself into a mental health clinic for three weeks over summer.

"I had a conversation with him about how important it is for us that we want the right people and good people at our club," Arthur told NRL.com after Ferguson's signing was announced.

"We're going through a period where we want to make sure that everything we do on the field and off the field is professional and meets the standards and expectations required by our club.

Roosters winger Blake Ferguson.
Roosters winger Blake Ferguson. ©NRL Photos

"He's fully aware of his responsibilities and accountability to his teammates and the club and he wants to be one of the players that can lead that."

Ferguson has run for almost 400 metres more than any other player in the competition and scored 10 tries from 15 games.

His impressive showings at club level have not been enough to reclaim his NSW Origin jumper, with Brad Fittler looking elsewhere after an ill-fated drinking session with Josh Dugan dominated the fallout from the Blues 2017 series loss.

The Eels have not guaranteed him a concrete position in their backline, with Ferguson able to play wing, centre and fullback. 

A number of current Parramatta players, including Bevan French and the off-contract Jarryd Hayne, also fit into that category.

Regardless, Ferguson looms as the big body the club has sorely needed since the departure of fan favourite Semi Radradra to French rugby last year.

"We'll have to wait and see [where Ferguson plays in 2019], but he's going to help us out of the backfield," Arthur said.

"He can play centre, he can play wing. He's a big body and he’s probably the form outside back in the comp at the moment.

"He's a quality finisher and is good at getting sets started out of the backfield."

The Eels will be Ferguson's fourth club after stints with the Roosters, Cronulla and Canberra, the last of which saw him sacked by the Raiders around off-field issues.

His signing will see him join prop Junior Paulo as Parramatta's big-name acquisitions for next season, with a roster overhaul gathering momentum as Arthur battles to avoid the wooden spoon.

Manly's Shaun Lane will also be in Blue and Gold next season, while the club has money to play with after Beau Scott's retirement due to an ACL rupture.

A call is yet to be made on a new deal for Hayne with Ferguson's arrival only increasing pressure for backline positions at the club.