Broad beaming with pride at England's character after thrilling Newlands triumph
The tourists started the day needing eight wickets to seal victory but they were frustrated by Pieter Malan (84) and Quinton de Kock (50) in Cape Town.
England still needed five wickets in the final session, and their all-time leading wicket taker James Anderson bowled only two overs after lunch amid fears of another injury.
However, De Kock holed out to a senseless shot off Joe Denly before Ben Stokes (3-53) finished off the tail as England won by 189 runs inside the final hour.
"[It is] very special, the crowd has been exceptional today, it's been an incredible day's play and a great Test match," Broad said.
"We had to work incredibly hard, we knew we were going to do that from yesterday's play.
"Incredible discipline from South Africa throughout the day but we kept saying all the time, 'One bit of magic', tried some funky fields, one breakthrough and we can apply some pressure. Fortunately we got that.
"On pitches like that, you need a bit of luck chasing 10 wickets and then you need a hell of a lot of character and skill.
"Stokesy finishing with the catching towards the end is something we've worked a lot towards.
"We're very proud of the character we showed throughout the Test match."
Stokes' all-round performance was once again key, the 28-year-old's 47-ball 72 allowing England to declare on 391-8 in their second innings.
His innings had come alongside maiden centurion Dom Sibley, who was elated his unbeaten 133 eventually came in a winning cause.
"Amazing win. Amazing atmosphere as well - it felt like a home game at the end," Sibley added.
"We were a bit flat but things changed quickly. Stokesy turned it on and produced a hell of a spell.
"I've lost two [Tests] and drawn one so it's nice to get a win on the board. To do it in that manner was amazing.
"It's nice to get the win and nice to have contributed. An amazing feeling and hopefully it continues."