Mbappe now has 27 goals in 31 LaLiga games this season, which has him sitting third on the European goalscorers' table.
Liverpool star Mohamed Salah lost his lead two weeks ago, with the Egyptian striker being overtaken by Sporting CP's Victor Gyokeres, who has scored 38 league goals and is now in the lead despite Portugal's Primeira Liga having a lower coefficient than the top five European leagues.
Mbappe is now three points away from Gyokeres' leadership after his Montjuic's exploits.
European Golden Boot table:
Victor Gyokeres (Sporting) (coefficient 1.5) 57
Mohamed Salah (Liverpool) 56 points
Kylian Mbappé (Real Madrid) 54
Robert Lewandowski (Barcelona) 50
Harry Kane (Bayern Munich) 50
Mateo Retegui (Atalanta) 48
Alexander Isak (Newcastle) 46
Mika Biereth (Sturm Graz/Monaco) 42.5
Erling Haaland (Manchester City) 42
Omar Marmoush (Eintracht Frankfurt/Manchester City) 42