The Hawks, 4-0 to start a year for the first time since 2014, kept top spot on the ladder after the 10.16 (76) to 9.10 (64) result at a blustery Launceston on Saturday night.
All 11 first-half goals were scored with the wind, with GWS opening up a 37-2 lead at quarter time.
Hawthorn came to life at the back-end of the second term with the breeze at their back, kicking six goals in 13 minutes for a 46-39 halftime lead.
Will Day and Nick Watson were heavily involved and both also had nice touches as Hawthorn broke the back of GWS with four straight majors at the end of the third against the trend.
Giants gun Jesse Hogan, who topped the goal tally with four on return from a broken thumb, set up a tense finish when he cut the margin to 12 with less than three minutes on the clock.
But Hawthorn scrambled well to hold on in front of a 14,021-strong crowd.
Hawthorn, who have a bye next weekend, knocked off Sydney, Essendon and Carlton in the opening three rounds.
The previously-undefeated Giants were near full-strength, with reigning Coleman Medallist Hogan back and Jake Stringer making his club debut in two big inclusions.
Hogan made an impact early with two goals in the first term when his side had the running.
Hawthorn, meanwhile, shared the majors between nine players, with veteran Jack Gunston getting a double.
Hawks big man Lloyd Meek outpointed the GWS rucks and finished with 31 hitouts, while Cam Mackenzie had a team-high 30 disposals.
Despite the final score, the Hawks barely got a shot on goal in a first quarter in which they trailed inside 50s 22-6.
They had the yips in front of goal with the gale behind them early in the second, with Gunston and Mabior Chol missing gettable shots.
But they found their composure despite a brief light tower outage.
