A beautifully paced run-a-ball 116 from the Nottinghamshire batsman on a slow surface laid the foundations before Jonny Bairstow and the lower order upped the ante to post 368 for seven.
England scored 127 from the last 10 overs, with Bairstow clearing the rope six times in his blistering 58, before Chris Jordan and David Willey added further late impetus.
Reece Topley and David Willey then struck early and South Africa A eventually folded for 205 in only 30.5 overs.
Hampshire left-armer Topley, leg-spinner Adil Rashid and Sussex seamer Jordan all took three wickets in a convincing display from Eoin Morgan’s side, despite some notable resistance from Theunis de Bruyn, who made an unbeaten 73.
Jordan also took three slip catches in an excellent all-round display.
Morgan won the toss in clear conditions and opening pair Jason Roy and Alex Hales added 49 before falling in quick succession.
Roy had just hoisted Marchant de Lange over long-off for six, when at the other end he was lbw to a full delivery from David Wiese’s second over for 22.
Hales made 23 but then looped de Lange to mid-on, before Taylor and Morgan shared an 80-run stand.
Morgan fell to a superb caught-and-bowled grab by Wiese for 41, and Moeen Ali hit Aaron Phangiso over the leg-side for a couple of sixes before he was run out backing up.
Taylor fell to mid-off in the penultimate over after reaching his 15th List A century, but by then the damage had been done.
Topley swiftly removed Dean Elgar with one that swung slightly to induce an edge to Jordan at slip.
Reeza Hendricks was bowled through the gate by Willey, Qaasim Adams nicked Topley to slip and Rashid turned one that snared Khaya Zondo’s edge as three wickets fell for seven runs.
Jordan ended a fifth-wicket stand of 73 when Dane Vilas chopped one on, and Rashid – returning from a successful stint in the Big Bash – nabbed two late wickets.