Born in 2010, Vega is a Spain Under-16 international and a regular fixture in Madrid regional selections. He began his career at Gimnastica Colmenarejo before moving to Getafe to continue his development, then signed for Real Madrid in 2024, where he has spent the past two seasons.
Primarily a left winger who can also play as a second striker, Vega has signed a three-year contract with Atletico.
"I'm really excited and looking forward to getting started," Vega said after putting pen to paper.
"I want to keep growing and taking steps until, hopefully, I can reach the first team."
The Madrid-born winger arrives having just won the Cadete Superliga title with Real Madrid, scoring seven goals in 25 games in a season during which he lost some prominence in the closing months.
The move continues an intense rivalry between the two Madrid clubs over academy talent, with Atletico Madrid responding after seeing several of their own young players move in the opposite direction to Valdebebas in recent years.
More than ten Atletico academy players under the age of ten have left the club for Real Madrid over the past three seasons, making the recruitment battle between the two rivals increasingly intense at youth level.
The transfer follows Real Madrid's own recent swoop for 15-year-old right-back Adrian Bielsa, and comes just days after Atletico saw a young prospect move in the other direction to Valdebebas, underlining how competitive the market for the capital's best teenage talent has become.
Vega is regarded as one of the most promising players in his age group in Spanish football, and Atletico will hope his development can follow a similar path to other academy graduates who have progressed through Juvenil A and into senior football at the Metropolitano in recent years.