Goal from Sergio Ramos, Lucas Vázquez and fellow teenager Vinícius Júnior had the match well out of reach before Brahim stepped on the pitch.
But the youngster still called the experience “unforgettable” after his first showing at the Bernabeu.
"This is great, an unforgettable and unique day,” he said after the match.
"Making my debut at the Bernabeu is great. This is a dream since I was a child.
"Winning makes the dream greater, but I take everything in peace. I will hang my debut shirt in my room."
Encantado de conocerte, estadio Santiago Bernabéu. ¡Gracias a todos por el recibimiento! ¡A por más! pic.twitter.com/Qp5lmK7c7P— Brahim (@Brahim) January 9, 2019
Vinícius was the star of the night, scoring a stunner before being replaced by Brahim, but the former Man City man had a good showing after coming on for the Brazilian, and says that one of Madrid’s veterans had praise for him after the match.
"Sergio Ramos has congratulated me and told me to continue like this, and that I will have many minutes,” he said.
"He is a top player and playing with him is to enjoy the moment and this dream."
Madrid are dealing with a host of injuries and have a crowded schedule in the next week, meaning Brahim could be back on the pitch sooner rather than later.
Los Blancos return to the pitch Sunday to take on Real Betis in a league match, with the club sitting fifth in the table and looking to gain ground on the leading pack.