The London-born singer, who already has a clutch of Grammys to her name, added to her awards haul at Sunday's ceremony, when she won Best Original Song for Skyfall.
And speaking from the red carpet at his annual Aids fundraiser viewing party, Sir Elton said the 24-year-old was the epitome of what "an entertainer should be".
"She's authentic," he explained.
"She doesn't lip-synch, she comes on and she sings, she's the real deal.
"She's not slick, she's human, she's imperfect, she's what every entertainer should be."
Adele, who had performed Skyfall live for Hollywood's biggest names earlier in the evening, was visibly moved as she picked up the Oscar, thanking her co-writer, Paul Epworth for "believing in me all the time".