The 22-year-old, who represented Australia at the World Cup earlier in July, was caught speeding twice overnight, NSW Police said on Friday.
Driving a BMW, Volpato was allegedly clocked at 109 km/h - nearly 50 km/h over the designated speed limit - when police stopped him on Sydney's Anzac Bridge at 1.10am on Friday.
He was subjected to a roadside drug test which allegedly returned a positive result for cocaine, police said in a statement on Friday.
A secondary sample of oral fluid was taken for further analysis.
His international driver's licence was suspended for six months.
Volpato had earlier been stopped at 11.05pm on Thursday, police said, for travelling between 86 and 94km/h in a 60 zone.
He was given a fine.
Volpato returned a negative result when he was given the initial roadside breath test.
Football Australia has been contacted for comment.
Volpato, who plays club football for Italian side Sassuolo, made three appearances for the Socceroos at the World Cup.
He made headlines shortly before the tournament when he switched his international allegiance from Italy to Australia.
Volpato, who was born and raised in Sydney and played his junior football at Sydney United 58, Sydney FC and Western Sydney before moving overseas, represented Italy at U19 and U20 level.
The 22-year-old, who has scored seven goals in his three seasons with Sassuolo after two seasons with fellow Serie A club Roma, said in March he was "waiting for Italy" to select him for the senior side, who subsequently failed to qualify for the World Cup.
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