Rayo competed in one European competition, the UEFA Cup in the 2000–01 season.
The club reached the quarter-finals before losing to Spanish club Alaves 4–2 on aggregate.
By historical standards, Rayo is the third best club in the Community of Madrid after Real Madrid and Atlético Madrid.
Rayo Vallecano was founded on May 29, 1924 in the hometown of Prudencia Priego, the wife of the club's first president, Julian Huerta.
Inspired by River Plate, in 1949, after an agreement with Atlético Madrid, a red diagonal stripe was added to the team's kit, and the club qualified for the Tercera Division for the first time in its history.
One of the constants of Spanish football, always in the shadow of the city's two biggest clubs, Rayo Vallecano spent many years in the 1980s and 1990s moving between La Liga and Segunda División.
The 1983–84 season was the worst of the 1980s.
The club finished in last position in the Segunda Division and were relegated to Segunda Division B.