Tim Goodacre 43, and son Jack, 12, made the live rounds of the ITV show after judge Cowell was bowled over by the mesmerising harmonies on their self-penned song The Lucky Ones.
Cowell fought back tears as he told them they reminded him of himself and his son Eric, four.
He said: “That was fantastic. I love that song. It reminded me of my boy and me.”
Fellow judge Amanda Holden said she had been “a mess throughout the whole thing”.
Tim and Jack, pictured, from Eccleson-Sea, Norfolk, said the tune was written as a tribute to Tim’s mother Angela and grandfather Jack, who died the same week in 2015.
Stay-at-home father Tim said: “It’s nice to know they’ll be looking down. The song is just about us taking stock every day and being grateful for what you have.”
Tim has sung in pubs and clubs and Jack performed in the West End stage musical School Of Rock.
Last year he reached the semifinals of ITV’s The Voice Kids.
