The Copa del Rey 1918 was the 18th staging of the Copa del Rey, the Spanish football cup competition.
The competition started on 8 April 1918, and concluded on 2 May 1918 with the final, held at the O'Donnell in Madrid, in which Real Unión lifted the trophy for the first time (second time counting the trophy won by Racing de Irun in 1913) with a 2–0 victory over Madrid FC with Juan Legarreta netting both goals for Unión.
Teams
North Region: Real Unión
Central Region: Madrid FC
South Region: Recreativo de Huelva
Galicia: Fortuna de Vigo
Asturias: Sporting de Gijón
Catalonia: RCD Español
Quarter-finals
Recreativo de Huelva and Fortuna de Vigo received a bye to the semi-finals. Real Unión and Sporting Gijón played a single match at a neutral venue, instead of a two-legged tie.
First leg
Second leg
RCD Español and Madrid CF won one match each. At that year, the goal difference was not taken into account. A replay match was played.
Replay
Madrid FC advanced to the semi-finals
One-legged game
This was a one-legged match, played on neutral ground. Real Unión advanced to the semi-finals.
Semifinals
First leg
Second leg
Madrid FC won 2–0 on aggregate matches.
One-legged game
This was a one-legged match, played on neutral ground, and it was Real Unión who advanced to the final with a 4–1 win.