The Germany Under-16 international netted after eight minutes of Dortmund's meeting against Inter to become the competition's youngest goalscorer.
Moukoko does not turn 15 until next month, meaning he smashed the previous record – 16 years and 30 days, held jointly by Ajax's Youri Regeer and Christos Liatsos of Olympiacos.
After scoring 50 goals during the 2018-19 campaign, Moukoko earned promotion to Dortmund's under-19 setup for this season and has caught the eye of Germany boss Joachim Low.
"I've been speaking to [Dortmund U19 coach] Michael Skibbe for a while," Low told the Bundesliga's official website. "Everyone involved is well advised to wait and let [Moukoko] develop in peace."