Benzema's two goals take him to 21 league goals for the season
Real Madrid went level on points with Atletico Madrid at the top of La Liga with a win at Cadiz in a week dominated by the announcement and seeming collapse of the European Super League.
There were fan protests outside the ground against the new league, which Real had intended to compete in.
Inside, the visitors ran riot, sealing the win with three first-half goals.
Karim Benzema scored twice – the first a penalty – and provided the assist for Alvaro Odriozola to head in.
The result gets Real's La Liga challenge back on track after the minor slip in drawing 0-0 at Getafe on Sunday.
It was on the same evening that they and 11 other leading European clubs were announcing their plans to form a breakaway Super League – a project that has seemingly now collapsed just three days later.
Real president Florentino Perez has been one of the most vocal advocates of the proposed competition, telling Spanish TV show El Chiringuito de Jugones that it had been devised "to save football".
Real have still yet to announce their withdrawal from the Super League, despite the majority of the rest of the clubs doing so, including all six English sides.
They will certainly qualify for next season's Champions League, but they are currently in a fascinating four-horse race at the top of La Liga to decide if that will be as Spanish champions.
With Benzema firing they certainly have a good chance.
The French striker coolly slotted in his penalty, after VAR was used to rule on the illegality of Isaac Carcelen's trip on Vinicius Junior.
He then swung over a perfect cross for Odriozola to head the second before nodding in the third himself from Casemiro's cross – all three goals coming in the space of 10 minutes.
As they ave in England over the last few days, fans gathered outside the Ramon de Carranza to protest the Super LeagueNine of the 12 clubs – including La Liga leaders Atletico Madrid – have withdrawn from the proposed Super LeagueLine-upsMatch StatsLive Text
1Ledesma20Carcelén3Jiménez Jarque4López Gutiérrez22Espino7Sánchez Ponce2Jonsson6Martín-Bejarano Serrano25Izquierdo18Negredo21Sobrino1Ledesma20CarcelénBooked at 29minsSubstituted forAkapoat 45'minutesBooked at 90mins3Jiménez Jarque4López Gutiérrez22EspinoSubstituted forAlejoat 65'minutes7Sánchez PonceBooked at 8minsSubstituted forLozanoat 45'minutes2JonssonBooked at 41mins6Martín-Bejarano SerranoSubstituted forTorres Ruizat 45'minutes25Izquierdo18NegredoSubstituted forSaponjicat 45'minutes21Sobrino
5Garrido9Lozano11Pombo12Saponjic13Gil14Alejo15Akapo16Torres Ruiz17Fernández19Alcalá24Malbasic37Martín Valerón
1Courtois3Militão5Varane6Nacho19Odriozola31Blanco14Casemiro12Marcelo25Rodrygo9Benzema20Vinícius Júnior1Courtois3Militão5VaraneBooked at 22minsSubstituted forCarvajalat 61'minutes6NachoBooked at 46mins19OdriozolaSubstituted forIscoat 61'minutes31Blanco14Casemiro12MarceloBooked at 68minsSubstituted forGutiérrezat 74'minutes25Rodrygo9BenzemaSubstituted forMarianoat 74'minutes20Vinícius JúniorSubstituted forAsensioat 61'minutes
2Carvajal11Asensio13Lunin22Isco24Mariano26Altube30Arribas32Chust35GutiérrezReferee:Antonio Miguel Mateu Lahoz
Home TeamCádizAway TeamReal MadridPossessionHome38%Away62%ShotsHome14Away14Shots on TargetHome3Away4CornersHome7Away3FoulsHome13Away21
Match ends, Cádiz 0, Real Madrid 3.