The team arrived in the early hours at Ezeiza city airport, where despite it being around 3am local time (7pm Tuesday NZ time) thousands were waiting with banners, flags and flares, and howling in joy at the victory, which came 36 years after the country's last World Cup victory.
By around midday in Argentina hundreds of thousands had congregated in downtown Buenos Aires, with major roads shut down for the parade. People held up banners of Messi and late icon Diego Maradona, played instruments or climbed lampposts or bus stops.
"It's crazy, it's incredible, it's the best thing that can happen to you in life," said Matias Gomez, 25, a metalworker.
"It is an enormous joy to see all these happy people, all together, one with the other, holding hands, giving each other hugs, kisses. We are all one today."
The Argentinian capital had been in party mode since the dramatic victory over France in Monday's final in Qatar, which has helped mask economic woes in the South American nation battling one of the world's highest inflation rates.
The victory, in a penalty shootout after a whipsaw game, made the country world champions for the first time since Diego Maradona hoisted the trophy in 1986 and the third in total.
The government made Tuesday a national holiday to allow fans to celebrate the win.
The players, after spending a few hours at the Argentine Football Association (AFA) facilities near the airport, left on an open-top bus with signs saying "World Champions" and three stars to mark the country's trio of trophies.
The players danced and cheered with fans who circled the bus.
Police had to hold people back to allow the vehicle to move forward on its slow journey toward the centre of town.
Earlier Messi, 35, who had burnished his reputation as one of the world's greatest players, sent out a message on Instagram saying "Good morning!" with a photo of him sleeping in his room at the AFA complex next to the golden trophy.
Messi had said the final - where Argentina beat France 4-2 on penalties after a scintillating 3-3 draw after extra time - would be his last match in the World Cup, though he intends to play a few more games for the national side.
The atmosphere at home had been so festive that at times it felt the whole country was partying through the night from Sunday onwards, in the southern hemisphere summer - the joy of victory infecting everyone, and drivers regularly blared their horns in celebration.
"There are people lying on the floor who came straight from the last party to get up and keep partying," said Elio Maisares, 25, as he celebrated in the city where everyone and everything was covered in the white-and-blue of the "Albiceleste" team.
"Just look at all this, look at everything that is painted in light blue and white. Along the roads, the highways, all the people are rooting for Argentina," he said.
"It's really impressive, it's unique, what a way to cry. I cried this morning, yesterday, the day before yesterday, I can't cry anymore, it's incredible!"