The Magpies were too classy and overwhelmed their opponents, with Cox one of 10 goal-kickers for his side in the 18.12 (120) to 7.13 (55) win on Sunday at the MCG.
It was the first time Collingwood have posted a triple-figure score since round two.
The Magpies (8-1) sit one win clear of their nearest rivals and now ride a five-match winning streak into a meeting with traditional foes Carlton in round 10.
Cox starred in his second game back from a lacerated spleen, the ruck-forward tallying 25 hit-outs, 19 disposals, four contested marks and four clearances.
The American cult hero, in his 98th AFL game, also kicked two goals as chants of "U-S-A! U-S-A!" rang out around the ground.
Cox's most influential display since his match-winning 2018 preliminary final showing came with the Magpies desperately needing him to stand tall, with first-choice ruckman Darcy Cameron (knee) still sidelined.
Jordan De Goey was best afield in the first half and finished with one goal from 31 touches as he racked up 12 contested possessions, 10 score involvements and seven clearances.
Jamie Elliott kicked three goals and Brody Mihocek, Beau McCreery, Bobby Hill, Jack Ginnivan and Will Hoskin-Elliott had two each.
Young star Nick Daicos compiled a game-high 41 disposals despite close attention from Xavier O'Halloran for periods and Tom Mitchell (36) was busy in the midfield.
Hill provided an early spark, kicking the opening goal against his former club with a sublime dribbling effort from the pocket.
The small forward had two goals by quarter-time as the Magpies led by 15 points.
Cox's 50-metre set shot extended the margin, which grew to 38 points before the Giants stemmed the flow.
The plucky visitors made it a contest until goals to McCreery and Elliott gave Collingwood a healthy 41-point buffer at the last change.
Ginnivan could only shake his head when his hack off the ground from 45 metres rolled through for a goal to continue the Pies' charge in the final term.
Emerging star Tom Green (30 disposals, eight clearances), former captain Stephen Coniglio and Lachie Ash (both 32 touches) battled hard in the middle for GWS.
Giants key forward Jesse Hogan kicked three goals.
12°C