With Webber in the bin, England got on the board through the dangerous Marcus Watson and it was game on again.
But Webber redeemed himself in stunning fashion as he returned to the field after his brief hiatus and put in a perfectly-placed kick for 17-year-old Rieko Ioane who scored to give New Zealand a 15-7 halftime lead.
Defence has been a hallmark of New Zealand's performance this weekend and the likes of Webber and Scott Curry have been at the heart of the action with reliable tackling.
Curry then got a try himself as the Mexican Wave erupted around an undersized but vocal Westpac Stadium crowd.
Ioane, a player who needed a dispensation to play at the tournament due to his tender years, completed his brace and with the score at 27-7, the party hit full swing. England scored a couple of late tries but it didn't help.
New Zealand 27 (Rieko Ioane 2, Dylan Collier, Gillies Kaka, Scott Curry tries; Beaudein Waaka con)
England 21 (Marcus Watson, Tom Mitchell, John Brake tries; Christian Lewis-Pratt 3 con)
HT: 15-7
6.03pm: New Zealand march into final
New Zealand are one game away from defending their Sevens Wellington crown.
They've knocked off South Africa 17-7 in their semifinal this evening and will meet their Pool B sparring partners England in the showpiece game later tonight.
England made their way to the final after they overcame a 19-0 deficit to run down Scotland after the hooter 24-19 in the day's first semifinal.
New Zealand captain DJ Forbes missed the semifinal win over South Africa as a dodgy foot kept him on ice; rookie Dylan Collier started as a result of the shuffle.
South Africa have proven a thorn in the side of the New Zealanders in recent years and lead the world series standings after the first three tournaments of the season.
Despite losing Seabelo Senatla to the sin bin late in the first spell, South Africa were able to knot the game up at 7-all as Kwagga Smith scored. Smith's try negated the earlier score from Joe Webber for New Zealand.
Webber's pace and ability to beat the first tackler has been a feature of his play this weekend.
Scott Curry, who has been one of New Zealand's best during the tournament, then made a huge play as he delivered a crunching cover tackle and then helped create a turnover.
Curry then stormed off down field and fed the ball to Jack Goodhue who crashed over to give New Zealand the lead.
With a minute left Rieko Ioane, who is only 17, then sealed it as he gobbled up a poor South African kick and bolted away to score.
New Zealand 17 (Joe Webber, Jack Goodhue, Rieko Ioane tries; Gillies Kaka con)
South Africa 7 (Kwagga Smith try; Branco du Preez con)
HT: 7-7
3.03pm - New Zealand book semifinal place
New Zealand have moved on to a semifinal meeting with South Africa at Sevens Wellington after defeating Australia 26-7.
Australia, who finished second in Pool C behind Fiji, posed a stiff quarter-final challenge for New Zealand this afternoon but the home side were able to get the spoils over their transtasman rivals.
Gillies Kaka had New Zealand on the board inside the opening minute and they went to the break with a 19-7 advantage as Sam Dickson and Joe Webber also crossed.
Webber, a try-scoring machine on the sevens circuit, showed electric pace during his solo effort as he left some Australian defenders clutching at shadows. When Kaka completed his double with a minute left in the second spell, the game was sealed.
New Zealand coach Gordon Tietjens has been working with a young group of players this weekend, including five Wellington first-timers, and they've blended in well with the experienced men.
The loss of Tim Mikkelson (groin injury) was damaging to New Zealand's title hopes but they're now two victories away from defending their Wellington crown. They topped Pool B yesterday with three wins from as many games.
South Africa will be no pushover in the semifinals though. They lead the world series standings after three tournaments and have plenty of pace out wide.
New Zealand's scrambling defence has been one of their strengths this weekend.
New Zealand 26 (Gillies Kaka 2, Sam Dickson, Joe Webber tries; Kaka 2 con, Beaudein Waaka con)
Australia 7 (Cameron Clarke try; Clark con)
HT: 19-7
