New Zealand won a Test series against South Africa for the first time with Kane Williamson hitting an unbeaten century Friday to steer them to a seven-wicket victory in the second Test.

Williamson's unbeaten 133 was at the heart of their 269-3 in the fourth innings of a tight Test in Hamilton to complete a 2-0 series win over the understrength tourists.

The Black Caps hadn't beaten the Proteas in 17 previous Test series dating back to 1931, having lost 13 and drawn four.

The 33-year-old Williamson was methodical throughout a 260-ball stay, putting on an unbroken stand of 152 with Will Young, who scored 60 not out, as New Zealand reached their target of 267 late on day four.

The in-form Williamson scored his seventh century in his last seven Tests, which included twin tons in the 281-run first Test victory at Mount Maunganui.

His 32 centuries have come from 172 innings, surpassing Australia's Steve Smith (174 innings) as the fastest player in Test history to reach that milestone.

Williamson batted through the day after New Zealand resumed at 40-1.

The 33-year-old adopted a disciplined approach on a tricky pitch but was always prepared to punish loose deliveries, scoring 12 fours and two sixes.

"It was very much a patience game and both teams were aware of that," Williamso n said.

"It was just about trying to put the ball in the right area for long periods with the ball and as batters we were sticking our toes in. It was a bit of old-school Test cricket I suppose.

"Credit to South Africa, certainly for the first couple of days they out-
played us. We had to fight hard to get out of that position and change the momentum."

New Zealand seamer Will O'Rourke finished with nine wickets on his Test debut to earn the man-of-the-match award, with Williamson named player of the series.

New Zealand briefly wobbled when opener Tom Latham was dismissed in the first session for 30 and Rachin Ravindra soon after lunch for 20, but Young dug in to reach his seventh half-century.

The inexperienced Proteas struggled to make an impact aside from Dane Piedt, who finished with 3-93 to give him eight scalps in his first Test in more than four years.

Offspinner Piedt struck early by removing Latham, the opener caught by Zubayr Hamza driving to short cover after adding nine to his overnight score.

Ravindra was undone by a near-identical shot after New Zealand had resumed the second session at 107-2.

South Africa were fielding a side missing the majority of their first-choice players, who skipped the series to instead contest their lucrative domestic Twenty20 league.

Captain Neil Brand was one of seven Proteas to make their Test debut in the series.

Brand lamented losing their last six wickets for 33 runs late on day three to relinquish a commanding position after the Proteas led by 31 runs on the first innings.

"I'm definitely more disappointed after this Test match, just because we were in the game," he said.

"The last session yesterday probably cost us a bit but we were still
confident coming into this morning and, to be fair to our bowlers, they left nothing out there."

Brand described the series as an "awesome experience" and hoped some of his players had done enough to earn ongoing selection for South Africa.