Los Angeles - Georgia Harrup, 27, stunned coaches will.i.am, Kylie Minogue, Tom Jones and Ricky Wilson with her rendition of Ray Charles' Hallelujah I Love Her So and puts her vocal ability down to "good genes".
The call centre worker - whose dad Albie is the brother of Adele's grandmother - didn't know she was related to the 25-year-old singer until 2009, when she was already a fan of her debut album 19.
Georgia told The Sun newspaper: "One day my dad rang his family and asked how everyone was doing and they said, 'Adele is on tour, doing really well".
''He asked what she was doing touring and they said, 'She's that Adele'.
''He came off the phone and told me that the person whose album I loved was related to me. I couldn't believe it, as she was always a massive inspiration to me anyway.''
Georgia, from Huddersfield, West Yorkshire, has only met the Skyfall hitmaker once at a family party and insists she's not using the star as an easy way into the music industry.
She explained: "I didn't want to push my career in her face so she felt obliged to help me. If she made contact I think I'd just sit there in a daze."
However, Georgia believes she gets her talent from her father, whose '60s band supported Jimi Hendrix on tour.
She said: "We've got good musical genes."
Listen to Georgia do a cover of Hit the Road Jack here: