The Brazil forward netted twice to guide Los Blancos to their second piece of silverware this season, at a packed Estadio de La Cartuja on Sunday (AEST).

For Carlo Ancelotti's side, victory ends a nine-year drought in Spain's most prestigious cup competition, with Madrid having last won in 2014 during the Italian's previous spell in charge.

But it is a tough result for Jagoba Arrasate's Osasuna to take, after Lucas Torro's strike had given the underdog hope of an upset in its first appearance in a Copa del Rey final in 18 years.

Madrid lived up to the favourite tag inside two minutes as Rodrygo swept Vinicius Junior's dynamite cutback past Sergio Herrera.

That early concession spurred Osasuna promptly onto the offensive, with Ante Budimir forcing Thibaut Courtois into a string of saves while Dani Carvajal had to hook Abde Ezzalzouli's effort off the line.

David Alaba struck the bar with an effort as Madrid aimed to double its lead, with Vinicius' hopeful appeals for a penalty falling on deaf ears on the stroke of half-time.

Madrid paid the price for those misses just before the hour mark when Torro struck a superb low strike beyond Courtois from outside the box.

Yet Madrid recovered and, after Toni Kroos saw his shot deflected, Rodrygo was on hand to pick up the pieces and prod another finish home.

Karim Benzema was unable to add gloss to the scoreline as Los Blancos was almost punished in stoppage time, only for Carvajal to make a last-ditch intervention to deny Kike Barja and ensure Madrid ended the long wait for a 20th Copa crown.