Dean stars with four wickets; Wong takes three wickets on debut
Dunkley hits her first ODI century - off 87 balls
Lamb and Beaumont put on 127 for first wicket
England now lead multi-format series 6-2
Highlights on BBC iPlayer from 07:00 BST on Saturday
Before I go make sure you check out my colleague Ffion Wynne's match report from Bristol by heading over here.
If haven't been able to follow all of today's game and clips, highlights will be on BBC iPlayer from 7am tomorrow morning (UK only).
Today was all about Sophia Dunkley though. Her magnificent 107 was the bedrock of England's innings and set them on course for victory.
Check out some of her best shots below, including one of the most outrageous sixes you will see this summer.
Here is how England won the game. First removing Marizanne Kapp before sealing victory with the wicket of Nonkululeko Mlaba.
England bowler Issy Wong: "I think I was more relaxed in my second over. Once I got that first spell out of the way, I got into it and I felt better. I think any seam bowler would love to take the new ball but that is a massive role. I am really grateful for that and any opportunity to wear my country's shirt with a new ball is a great one. I was very happy where I was today.
"I always try to stay grounded. I've done hard work to get there but there is still a lot of hard work to be done. I want to earn the right to take wicketz. It is not the best balls that get the wickets but the balls that come before that that allow the wicket to come."
Player of the match Sophia Dunkley: "It is nice to get some runs in my new role at number three and show what I can do. It was really set up by Tammy and Lamby, they did a great job and allowed me to settle in and get a partnership with Nat. A great day.
"It's just about going out and playing like I can, use the powerplay and play aggressively. It's great to have Nat and Heather behind me because they can manage the innings really well. So it is nice to play freely."
The secret to England's recent success: "We have just come in with really fresh mindset, we want to be aggressive and play freely and express ourselves. It is great to see and everyone has done so well so far."
England captain Heather Knight: "Really happy, a brilliant performance to back up the other day. It was probably even better. The way Tammy and Lamby at the start set up the innings perfectly and Sophia getting her first hundred, it is always special when that happens.
"We bowled them out again. We want to have that wicket mindset and I thought that was brilliant today. Sometimes when they get off to a flyer like they did and the scoreboard gets away from you it is easy to go a bit defensive, but I thought it was impressive how the bowlers wanted to keep attacking and keep taking wickets."
On Charlie Dean's performance: "Very important, a really aggressive, attacking off-spinner and fits the mindset of wanting to take wickets, particularly in that middle spell with her and Sophie Ecclestone, who have formed a really nice partnership. She may go for a few runs but the fact she is taking wickets really adds value to the team."
South Africa captain Sune Luus: "We knew it was a high-scoring ground and expected England to push for 300. We started off slow, the spinners pulled it back but that partnership with Nat and Dunkley, they batted really nicely.
"With the big chase you need wickets in hand. We still had 100 runs to get with 10 overs remaining, which is gettable. So lessons learned today. A good game of cricket and onto the next one.
On Marizanne Kapp's performance: "She is the senior player in our side and it is good she is leading from the front."
On what South Africa need to do in the final ODI: "We had glimpses of the cricket we want to play. It is just about searching for that all-round performance."
Marizanne Kapp was the pick of the South Africa batters. She showed a great array of shots in her 73 from 59 balls. She just ran out of partners in the end.
Melissa Story
BBC Test Match Special
South Africa never got close to England's dominating target. It's been an incredible performance from England.
First, the heroics of Lamb and Beaumont, and then Nat Sciver scoring and continuing her great run of form. The innings headlined by Sophia Dunkley's maiden century. And then wickets from Wong, Bell, Ecclestone and Dean.
Georgia Elwiss
England all-rounder on BBC Test Match Special
It's the complete performance and England will be very happy with that.
Issy Wong was magnificent today. She loves being the difference. She loves being the enforcer and the wicket taker. She loves putting on that England shirt. I see her doing that role for a number of years now.
The England players are jubilant as they celebrate that final wicket in the middle, hugging and cheering.
The players then wander off the field to huge the coaching staff before shaking hands with the South Africa players.
England win by a hefty 114 runs and take an unassailable 2-0 lead in the three-match ODI series.
They were mightily impressive today.
Mlaba c Dean b Ecclestone 0 (SA 223)
Game, set and match.
No.11 Nonkululeko Mlaba lasts just five deliveries before swiping the ball straight to Charlie Dean at cover.
England wrap-up a dominant victory!
Melissa Story
BBC Test Match Special
Fantastically done! A full delivery and a comfortable catch for Ecclestone's first wicket of the day. You feel it's very much coming to an end for South Africa now.
Kapp c&b Ecclestone 73 (SA 223-9)
Hmmm, maybe not.
Marizanne Kapp's wonderful innings is over and it's a underwhelming way to go as she dances down the track attempting to smack Sophie Ecclestone into the stand, but can only lob the ball up for a regulation caught and bowled chance.
Warm applause for Kapp as she makes her way from the field though, a very, very good innings
South Africa can't, can they?
A moment Lauren Bell will never forget as she claims her maiden ODI wicket.
Lauren Bell over-stepped with her second delivery, meaning a free hit.
Marizanne Kapp cannot take advantage though as she can only crack the ball to the boundary rider in the off-side.
Kapp looks to the heavens in frustration.
Like an arrow.
Lauren Bell gives Marizanne Kapp a bit of width, always dangerous, and Kapp plays a beautiful drive that fizzes through backward point for four.
Melissa Story
BBC Test Match Special
Kapp is tearing into Sophie Ecclestone here. Great shot!
Marizanne Kapp is seeing it like a beach ball. She nonchalantly strides forward and launches Sophie Ecclestone over her head for a two-bounce four.
The next shot is even bigger - Kapp dispatching Ecclestone over deep mid-wicket for six!