Amid speculation the 36 year-old Socceroos icon will join the A-League with Melbourne City, Cahill again displayed his goalscoring nous with a trademark header to put Hangzhou ahead in the fifth minute.
It was Cahill's fourth goal in 16 Chinese Super League appearances this season.
Australia and former Western Sydney Wanderers defender Matthew Spiranovic also played the full 90 minutes for Hanhzgou, who moved up to 13th place in the CSL, but only two points above the relegation zone.