Eoin Morgan's men had to chase down South Africa's 174 for eight after Surrey seamer Tom Curran had become the fifth England player to take three wickets on his worldwide T20 debut.
Jason Roy led the team from the front scoring a whirlwind 67 but got out in a freakish manner becoming the first batsman to get out for obstructing the field.
Liam Livingstone, who was making his debut for the hosts, was run out for 16 with two balls remaining meaning that England needed eight to win from the final two deliveries.
Mangaliso Mosehle fell shortly after, while Jon-Jon Smuts smashed 45 off 35 balls, which included four boundaries and three sixes, before he was dismissed by Liam Dawson.
England, who awarded debuts to Liam Livingstone and Tom Curran but opted against handing Craig Overton a senior bow on his home ground, won the toss and chose to field in front of a sell-out 12,500 crowd making the most of the national side's first appearance in Taunton since 1983.
The England vs South Africa 3rd T20I will be played at the Sophia Gardens in Cardiff. Andile Phehlukwayo and Paterson were dispatched to the rope and leg spinner Imran Tahir's first ball to him was greeted with a straight four. Chris Jordan's three for 31 and two for 22 from Tom Curran on his second appearance then helped derail the chase, with South Africa stuttering to 162 for seven by the end of their 20 overs.
Curran, the son of the late former Zimbabwe global Kevin, struck with just his second ball in worldwide cricket when Reeza Hendricks bottom-edged a pull into his stumps.
"We'll take it and run, but the on-field umpire told me at the time that the right decision was made".
"It was about the energy and showing the South African never-say-die, attitude.now we have a decider on Sunday", said De Villiers.
BOWLING: M Morkel 4-0-43-0, CH Morris 4-0-18-2, D Paterson 4-0-32-1, AL Phehlukwayo 4-0-34-1, JT Smuts 1-0-11-0, T Shamsi 3-0-24-0.
"It wasn't easy in that light", Morgan said.
But Morgan insisted England had only themselves to blame, saying: "We didn't deserve to win because we didn't capitalise on the start we had".
"We've always had a lot of competition in the playing XI". Especially in a format like T20 where you have to get going from the outset and don't have too much time to settle in.
Dawid Malan's 78 from 44 balls - the highest score by an England player on T20 debut - was the bedrock of England's 181 for eight at the SSE Swalec Stadium.