Travis Head, Mitchell Marsh and Cameron Green smashed blistering hundreds as Australia steamrollered South Africa by 276 runs in the final one-day international in Mackay on Sunday.

South Africa had already clinched the series, which they won 2-1 after Australia claimed the T20 series between the sides, and the 50-overs world champions were left playing for pride in the last match.

A 250-run opening partnership between player-of-the-match Head (142) and Marsh (100), and an incendiary hundred by Green powered Australia to a mammoth 431-2.

The hosts hit 18 sixes as they posted their second-highest total in ODIs - behind their 434 against the same opposition in 2006.

South Africa were all out for 155 in 24.5 overs with spinner Cooper Connolly completing figures of 5-22.

"A pretty crazy day, wasn't it?," Australia captain Marsh said.

"A full performance from the lads. Shame, it was a little bit too late but full credit to South Africa. They played outstandingly well in the first two games."

Electing to bat, Head and Marsh milked 86 runs from the first 10 overs to signal Australia's intentions.

With Kagiso Rabada missing the series due to injury and Lungi Ngidi rested for the final ODI, South Africa's pace attack lacked its usual firepower.

Australia raced to the 100-mark in the 13th over and Head reached his hundred off 80 balls, taking a single off spinner Senuran Muthusamy to reach the milestone.

Australia got to 250 in the 34th over but immediately lost Head, who was caught off spinner Keshav Maharaj after hitting five sixes and 17 fours.

Marsh, who also struck five sixes, brought up his hundred before he fell fluffing a slog-sweep to Muthusamy, but there was no respite for South Africa as Green produced a sensational display of power-hitting.

The all-rounder raced to a 47-ball hundred, his maiden and the second fastest by an Australian in an ODI, and blasted eight sixes in his unbeaten 118 off 55 balls. Alex Carey contributed 50 not out.

In reply, South Africa slumped to 50-4 in the ninth over and never recovered.

Dewald Brevis (49) and Tony de Zorzi (33) provided brief resistance but Connolly, backed up by superb catching from his teammates, ran through South Africa's middle order.

"We were under the pump from the first ball," South Africa captain Temba Bavuma said.

"They put us under pressure. They made it look like a very good surface...They were far better than us today."

Maharaj was adjudged player-of-the-series for his six wickets.