Worsfold met with Eagles chairman Alan Cransberg and chief executive Trevor Nisbett to inform them that he did not have the energy to continue as senior coach.
Cransberg and Nisbett announced Worsfold's resignation at a media conference, without Worsfold present.
"It's sad news for us," Cransberg said.
"I think that it’s important that John recognised that he didn’t have the energy and the passion and the enthusiasm and the emotion to keep going.
"He’s a man of great integrity.
"He very clearly said that from him point of view, now was the right time for him to move on and he also thought that the club was in a good position to put a new coach in place.
"John made that decision independently of the club and again that is something you will need to talk to him about the reasons, but he has basically said that the time was right for someone else to step in to the chair.
Captain Darren Glass and vice-captain Beau Waters were informed of the coach's decision by phone calls from Cransberg.
The players are on leave, so the club was unable to call them to a meeting and they were informed of Worsfold's departure by text message just before the media release was issued.
Worsfold issued a statement through the club.
"It's a really important decision for me and for the footy club.
"I have come to that decision around the fact I shouldn’t do the job if I don’t have the energy to give it absolutely everything; that wouldn’t be the right thing for the club and basically that’s where it got to.
"My time is done as coach of this footy club. I couldn’t have had a better time, I couldn’t have asked for any more. I certainly couldn’t have given any more."
It ends Worsfold's 24 years of formal involvement with West Coast.
He exits as the club's longest serving captain and coach.
He captained the Eagles in the 1992 and 1994 premierships and claimed the 2006 flag as coach, and also captained the club in the 1991 Grand Final and coached the 2005 grand final.
"He's the biggest contributor to the club, full stop," Nisbett said.
"He's an icon and his decision today is a historical one.
"It's something that is pretty unfashionable these days, but it's sad in some respects because we're losing such an icon - maybe we won't lose him from the club, but we'll lose him in a very senior capacity.
"He's an outstanding person and an outstanding contributor to our club.
"You will be looking at this club in 100 years' time and Worsfold will right up there as one of the people that helped build this great organisation and helped make it this sort of organisation that it is."
