Despite fielding two debutants and being without late withdrawals Steve Johnson (back) and Jared Rivers (knee), the Cats were 64 points up by half-time.
They powered on from there, racking up a much-needed percentage boost in prevailing 20.13 (133) to 5.7 (37).
Geelong's fifth straight win over St Kilda improved its 2014 record to 9-3 and kept it in touch with the top four.
The result also ensured Alan Richardson's battling side will end round 13 on the bottom of the ladder with just three wins from its 12 matches.
On a day when most Geelong players made an impression, Jimmy Bartel was among the best.
The 30-year-old roamed up and down the ground, finishing with 32 disposals, 13 marks and a goal.
Mathew Stokes (36 disposals) was another key contributor in the midfield, while Andrew Mackie provided plenty of rebound off half-back.
In the absence of Hamish McIntosh, who missed the game after being rested, Dawson Simpson dominated in the ruck, proving far too strong for St Kilda youngster Billy Longer.
Star forward Tom Hawkins dominated up forward, taking 13 marks and kicking three goals.
The home side had 11 goalkickers in all, with Joel Selwood, Josh Walker and Mitch Duncan also chipping in with three majors each.
Both first-gamers did their bit. Hartman tallied 14 disposals and five tackles, while Lang, who started in the green vest and was subbed in at half-time, gathered seven touches and booted a goal.
St Kilda, which last won at Geelong in 1999, started in brilliant fashion, with Maverick Weller bombing the opening goal just 13 seconds after the first bounce.
But there were few highlights for the Saints after that.
Midfielders Seb Ross and Farren Ray were their best four-quarter performers, but skipper Nick Riewoldt, who played as a loose man in defence at times, finished with just eight disposals and one goal.
Topping off a dark day for the club, Weller was reported for flattening Mark Blicavs in the third quarter.
The Cats will face a much tougher proposition when they travel to the Gold Coast to play the Suns at Metricon Stadium next Saturday.
The Saints host West Coast at Etihad Stadium the following day.
Twitter: @AFL_AdamMcNicol http://afl.to/adammcnicol
GEELONG 6.4 12.7 16.11 20.13 (133)
ST KILDA 1.2 2.3 2.5 5.7 (37)
GOALS
Geelong: Duncan 3, Selwood 3, Walker 3, Hawkins 3, Murdoch 2, Stringer, Bartel, Mackie, Stokes, Lang, Motlop
St Kilda: Weller, Riewoldt, Shenton, Billings, Armitage
BEST
Geelong: Bartel, Duncan, Stokes, Simpson, Motlop, Mackie, Hawkins
St Kilda: Ross, Ray, Shenton, Hayes
INJURIES
Geelong: Rivers (knee) and Johnson (back) replaced in selected side
St Kilda: Milera (ill) replaced in selected side
SUBSTITUTES
Geelong: Darcy Lang replaced George Horlin-Smith at half-time
St Kilda: Clinton Jones replaced Tom Lee in the second quarter
Reports: St Kilda's Maverick Weller reported in the third quarter for rough conduct against Geelong's Mark Blicavs, Geelong's Dawson Simpson reported for striking St Kilda's Jimmy Webster
Umpires: Farmer, Burgess, Armstrong
Official crowd: 25,180 at Simonds Stadium
