The 37-year-old striker, released by Juve after 19 years at the club in May, will be paid A$4 million over the two years of his contract with Sydney FC but was keen to emphasise that this was not the start of his retirement.
"I am here not for the end of my career but for the start of my new career," he told reporters in a media scrum outside the terminal building.
"I want to win some [titles]. I play to win."
Hundreds of chanting fans were already in place two hours before the 91-cap Italy international and his family emerged from the arrivals gate.
A huge banner created by "Juventus Club Sydney" welcomed him in his own language and there were plenty in the crowd from Sydney's large Italian community sporting the famous black and white shirt of the Turin club.
There was plenty of Sydney FC sky blue on show too, though, and the chants, with the exception of a few renditions of "c'e solo un capitano" or "there's only one captain", were mostly about their affection for their "harbour city" club.
"S-Y-D-N-E-Y, I am Sydney till I die, with a nick nack paddy wack give a dog a bone, Alessandro welcome home!" ran one.
Del Piero's wife and three children emerged first and the decibel level rose to new heights when the former Juventus captain finally greeted fans.
"I'm very happy," he said. "It's good to see so many people come out to welcome me, we start work tomorrow," he added in Italian.
Sydney FC chief executive Tony Pignata, on hand to welcome his new signing, said he was certain the gamble of offering Del Piero the richest contract in Australian sporting history would reap rewards both on and off the pitch.
"There's lots of anticipation for our first home match and I'm sure we'll have a big crowd," he told reporters.
"Over the course of the year, it will definitely pay off. He's just played a full season with Juve, he's been training since July and I'm sure he'll have a good year."
Sydney FC have won the A-League twice in the seven seasons of the league but were fifth last season and knocked out of the title play-offs in the first round.
The eighth season of the league begins in early October with Del Piero likely to make his debut against Wellington Phoenix in New Zealand on October 6.
A-League officials are hoping the arrival of such a big name in football will help them as they fight for a bigger share of the domestic sports market.
The world's most popular game lags behind rugby league in popularity in New South Wales, a factor not lost on at least some of the Sydney FC fans.
"Are you watching rugby scum?" they chanted with pride as Del Piero's car drove away from the terminal building.
