Madrid took the lead in bizarre circumstances in the 51st minute as Karim Benzema stuck out his leg to intercept Karius throw towards Virgil van Dijk.
The goal was perfectly legitimate, despite Karius protests, as the ball was technically class as in play once the Liverpool goalkeeper had thrown it out.
Sadio Mane equalised shortly after before Gareth Bales stunning overhead kick put Madrid back in front.
And Zinedine Zidanes side sealed the victory thanks to Bale and another error from Karius.
Bales strike from range had plenty of power but it was straight at Karius, although the Liverpool goalkeeper failed to read the shot and the ball slipped straight through his hands.
After the final whistle, Karius was reduced to tears and the 24-year-old approached Liverpools supporters to offer an apology.
Former Chelsea midfielder Frank Lampard slammed Karius for his mistakes in such a high-profile fixture.
At a human level you have to feel for Loris Karius, but mistakes like that dont belong at this level, he told BT Sport.
Theyre not for a Champions League final – the first one, I couldnt quite believe what I was seeing.
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