The Britain's Got Talent star admitted that she did not even realise the iconic performer knew who she was.
Boyle was at Falkirk Stadium on Sunday night (June 10) watching John when he gave her a shout-out in front of 15,000 fans.
He then invited the 'I Dreamed a Dream' star backstage for a chat.
"I almost fell off my chair when he announced that I was in the audience," Boyle told the Daily Record.
"I was surprised he even knew who I was. It's rare I'm speechless but on this occasion I was. The man is a musical genius and I was thrilled that I got to say hello backstage."
Boyle also revealed that she started recording her fourth studio album last week. The collection is expected to be released later in the year.
Watch Susan Boyle performing 'You Have To Be There' below: