Mbappe, 18, needed just three minutes to get PSG off the mark when he netted away to Anderlecht on Wednesday.
That goal was the ex-Monaco man's eighth in Champions League competition, a mark that has never been reached by anyone under the age of 20 in the competition.
Six of those strikes came in Monaco's thrilling run to the semi-finals in last year's competition, while Mbappe hit his first goal in the Champions League for PSG in a 5-0 drubbing of Celtic last month.
In total, the youngster has netted 31 goals in 67 appearances since his professional debut and, at just 18, there is plenty of time to extend his record as the most precocious scorer in Europe's flagship competition.
The previous highest-scoring teenager in Champions League history was Patrick Kluivert, whose exploits came for Ajax.