The Spain international tapped in from close range in the eighth minute after latching onto Jordi Alba's cutback.
⚽@ANSUFATI— FC Barcelona (@FCBarcelona) October 24, 2020
✅ 17 years old
✅ Youngest #ElClásico goalscorer in history
✅ Ties @LaLigaEN record for most goals ever scored by a player under 18 years old.
I N C R E D I B L E ! 🤯 pic.twitter.com/6nzYZmPJem
His strike cancelled out Federico Valverde's opener, which had come three minutes earlier during a frantic start.
At the age of 17 years and 359 days, Fati is the youngest player to score in a meeting between Barca and Madrid in the 21st century.
It is the latest in a long list of records set by the Barca academy graduate since he made his senior debut in August 2019.
Fati is also the overall youngest goalscorer for Barca and the Spanish national team, as well as being the youngest scorer in Champions League history.
He has established himself as a regular in Barca's frontline this season ahead of Antoine Griezmann and Ousmane Dembele, who both started on the bench against Madrid.
The early equaliser was the 400th goal scored by the Catalan giants against their bitter rivals in all competitions.