Haynes, the No.7 pick in the 2011 NAB AFL Draft, was one of two players from that draft class – along with Taylor Adams – who had yet to extend their original deals with the Giants.
With speculation one or two GWS players may be considering a return to their home states, Victorian Haynes has put the finishing touches on negotiations and extended his deal until the end of 2015.
Small forward Wilson has also committed for a further two years, bringing some good news at a time when the club has been under scrutiny following its heavy loss to the Sydney Swans on Sunday.
"I'm very happy," Haynes told AFL.com.au.
"Another two years and I'm looking forward to being at the Giants.
"As time's gone on I've become more used to Sydney and I love the city and love playing for the club.
"We've got new facilities coming along at Sydney Olympic Park, which will be top of the line and will be great for the future, and we've got a lot of talent on our list.
"We've lost some experienced players like Chad Cornes, Luke Power and James McDonald, so we're probably more inexperienced than last year.
"Hopefully next year, another year older and another pre-season, we can start winning some games."
Haynes struggled to adjust to senior football in his rookie year and concedes he didn't really earn the eight games he played, coming at a time when the club was casting an eye over at all of its young talent.
But the 21-year-old has added seven kilograms of muscle to his slight frame and is feeling much more comfortable.
Haynes played two games earlier this season before spending another two months in the reserves, but his past three appearances in the senior team have been his best at the top level.
"Last year I struggled a bit just trying to find the tempo of the game," he said.
"Obviously I've got a pretty light frame and it just took me a while to get up to the speed of the game and put a few more kilos on.
"The more games I play, the more experience I'm getting and the more comfortable I feel.
"This is probably the first time that I've actually earned my spot.
"It's just about gaining experience. We've got nothing to lose at the moment so I'm just going out there and having a crack."
Wilson was one of the Giants' 17-year-old access selections back in 2011 and he made nine appearances last season.
The 20-year-old has only played one game this year, but the highly skilled West Australian kicked three goals in the reserves' win over the Swans on Sunday and is close to a recall to the senior side.
James Dampney is a reporter for AFL Media. Follow him on Twitter @AFL_JD