Lionel Messi had blasted Barca ahead with a penalty in the first half but Mbappe pulled the French champions level with a classy piece of control and finishing to complete a flowing team move also involving Marco Verratti and Layvin Kurzawa.
Mbappe, who had not scored in the Champions League knockouts for two years before Tuesday, smashed PSG into the lead in the 65th minute while Moise Kean took advantage of some woeful Barca marking to head in a third goal for the visitors in the 70th.
The insatiable Mbappe looked hungry for more though and after being denied his third goal by Barca keeper Marc-Andre ter Stegen, he completed his treble in the 85th minute by curling the ball past the German into the top corner.
Barca overcame a 4-0 defeat to PSG in a last-16 first leg in 2017 by winning the second leg at home 6-1 and the Catalans now face another daunting task in turning this tie around when they visit the Parc des Princes on March 10.
Barcelona went into the game crowing from a run of seven La Liga wins in a row but, while they were boosted by the return of serial winner Gerard Pique in defence after nearly three months out, they were blown away by Mauricio Pochettino’s side.
In the other last 16 tie, Liverpool beat RB Leipzig 2-0 away thanks to goals from Mohamed Salah and Sadio Mane as the Reds snapped a three-match losing run.
Juergen Klopp’s team may have written off their chances of winning back-to-back Premier League titles after losing three successive domestic matches but they gained a clear advantage in their European tie going into the March 10 return leg.
Salah easily intercepted a back pass by Leipzig’s Marcel Sabitzer to put the visitors ahead in the 53rd minute and on course for their first win in any competition since late January.
Mane then pounced on another mistake when Nordi Mukiele failed to clear a long ball five minutes later, leaving the Germans down for the count in Budapest’s Puskas Arena where the game had been relocated due to COVID-19 restrictions in Germany. (Reuters)