Cameron again showed his potential to become an all-time AFL great by kicking his first seven-goal haul, and he was clearly best afield in the twilight match on Saturday at the MCG.
The Magpies only led by two points at three-quarter time, but kicked six goals to one in the final term to win 15.16 (106) to 10.6 (66).
Midfielders Dane Swan and Dayne Beams were best for the Magpies with 39 and 37 disposals respectively.
A loss would have been disastrous for the Magpies, who are only two games inside the top eight.
Vote for your top three players following Saturday's win to help decide who will take home the Magpie Army Player of the Year Award.
GWS remain winless, but were impressive for much of Saturday's match.
Cameron kicked the Giants' first five goals and now has 50 goals for the season, putting him third on the Coleman Medal tally.
It was the last game at the MCG as a player or coach for Giants mentor Kevin Sheedy.
Collingwood forward Ben Reid kicked the first goal of the game inside the opening minute, but Cameron replied soon after.
GWS suffered an early blow when key defender Tim Mohr was knocked out in a marking contest.
His replacement Adam Kennedy was also forced off the field in the third term because of a blow to the head, but returned to the field.
Teammate Will Hoskin-Elliott was concussed in the final term, the game held up for some minutes as the young Giant received medical treatment on the ground.
It became evident early in the first term this was going to be no cakewalk for Collingwood as Cameron fired and the Giants sniffed an opportunity.
Nathan Brown did not last on Cameron for long, with Keeffe moved onto the in-form forward before the end of the opening term.
A late goal to Beams meant the Magpies only trailed by four points at quarter-time, but they were clearly misfiring.
Mark Whiley performed a disciplined lockdown role on star Collingwood onballer Scott Pendlebury, and generally the Magpies lacked intensity.
Coach Nathan Buckley started coaching from the boundary line during the second term, his body language as he prowled the dugout reflecting a growing sense of concern for Collingwood.
Cameron continued to be the only Giants goalscorer when he put through his fifth early in the second.
Midway through the term, a undisciplined attempt to shepherd by Ben Sinclair at a kick-out meant a free kick to Devon Smith, who became the Giants' second goalkicker.
Dylan Shiel goaled on the run to give GWS an improbable 16-point lead at halftime.
Nothing symbolised Collingwood's plight more than the pro-Magpies crowd booing as the players left the field at halftime.
Collingwood kicked three goals in the opening three minutes of the third term to regain the lead, but the young GWS side did not give in, with Cameron kicking two goals in the term.
His second goal of the quarter was a beauty. With Lachlan Keeffe pressuring him, Cameron calmly tapped the ball ahead, hugging the boundary line before leaving Keeffe in his wake and goaling on the run.
GWS regained the lead 19 minutes into the term, but a goal to Jamie Elliott two minutes later meant the Magpies were in front at the last change.
The Magpies kicked six goals to nil in the last quarter as the lead stretched out to 40 points, but after last week’s loss to Gold Coast there is plenty for the club to work on in the lead in to finals.
Buckley said the Pies' first half was as bad as they have played this season.
"We were minus 17 in contested ball so it was really poor," he said. "You've got to give credit to the young players of GWS … Our work rate improved in the second half and we were a lot better after that …
"We're not playing our best footy. We need to go up a couple of rungs. We're under no illusions about that."
Sheedy was disappointed with the result but pleased with his side's development.
"The boys were very committed and it was probably one of our better performances on the MCG, not that we've played here a lot," he said.
"Our contested ball we were pretty good at, we moved the ball quite well, our kicking early was very, very good and some of our players were very courageous today, going for some balls that probably a lot of players might not have gone for over the years that I've coached."
Collingwood 3.3 4.6 9.12 15.16 (106)
Greater Western Sydney 4.2 7.4 10.4 10.6 (66)
Goals - Collingwood: Cloke 3, Swan 3, Sidebottom 3, Reid 2, Beams, O'Brien, Elliott, Witts
Greater Western Sydney: Cameron 7, Scully, Smith, Shiel
Best - Collingwood: Swan, Sidebottom, Beams, Shaw, Pendlebury, Grundy
Greater Western Sydney: Cameron, Shiel, Ward, Adams, Hampton
Injuries - Collingwood: Reid (ankle)
Greater Western Sydney: Mohr (concussion), Hoskin-Elliott (concussion), Kennedy (concussion)
Substitutes - Collingwood: Jamie Elliott replaced Ben Kennedy in the third quarter.
Greater Western Sydney: Adam Kennedy replaced Tim Mohr at quarter-time.
Reports: Nil
Umpires: Fila, Armstrong, Ryan
Official crowd: 32,691 at the MCG.
