Aged 17 years and 212 days, the striker beat the previous record by more than two years, surpassing Patrick Kluivert's mark from 1995, as he levelled Aston Villa's UEFA Super Cup clash with Paris Saint-Germain in Salzburg.
Villa ultimately lost 2-1 to two moments of individual quality from Khvicha Kvaratskhelia and Désiré Doué, but in Madjo, Unai Emery's side unearthed a genuine star in the making.
Standing 6ft 4in, the centre-forward dominated arguably the most imposing centre-back pairing in Europe, Marquinhos and Willian Pacho, and could realistically have scored four times before half-time.
His equaliser, which arrived just before the break, was in fact the hardest of the four chances presented to him: he held off Pacho at the back post to volley home John McGinn's cross, having already been teed up twice by headed knock-downs from his captain that he was unable to convert.
Madjo had waited 212 days for his competitive Villa debut, having first signed for the club in a shock £10 million deal from Ligue 2 side Metz back in January. FIFA initially barred Villa from registering him under rules preventing international transfers involving players under 18, only for the club to win an appeal through the Court of Arbitration for Sport earlier this month. Unai Emery threw him straight into the starting line-up against PSG and was rewarded immediately, with Villa's much-changed side matching the European champions for large periods of a brave, industrious performance.
The registration saga stemmed from Madjo's unusual background: born in Enfield, he was raised from a young age in Luxembourg before completing his development in France with Metz. Under FIFA rules, players under 18 cannot complete international transfers, but Villa successfully argued he should be exempt given his London birth.
That same technicality makes him eligible for England, despite having already played three non-competitive senior matches for Luxembourg last year. Although also eligible for Cameroon, the country of his parents' birth, Madjo has already committed his international future to England, scoring four goals in nine Under-17 appearances and featuring at last summer's European Under-17 Championship in Albania.
Having deputised expertly for the injured Ollie Watkins in Salzburg, Madjo will now turn his attention to making an impact in the Premier League, with performances of this calibre likely to put him firmly in the conversation for regular minutes at both club and international level in the season ahead.