The 71-year-old was seen shaking hands and chatting with Her Majesty at the Royal Academy of Arts in London, where she was presenting awards to five individuals who have made a national contribution to the visual arts or architecture.
Wearing a smart black suit and polka dot tie, Rod appeared thrilled as he chatted to the monarch alongside his wife Penny Lancaster.
It was a remarkable day for Sir Rod, who was knighted in recognition of his services to music and charity. The singer was joined by his wife and their two sons, Alistair, ten, and five-year-old Aiden, for the investiture ceremony hosted at the palace.
Speaking after the ceremony, Rod told reporters that he was on "cloud nine", and said that he and Prince William spoke briefly about his impressive music career, which has spanned six decades.
"We talked about music and he said 'It's great that you're still going' and I said: 'I have to – I've got eight children!" Rod revealed. "He congratulated me on my long career, and I said how happy this made me. I just wish my mom and dad had been here to see it."
The "Maggie May" singer had previously said it was a "monumental honour" to be knighted when the news was announced in the Queen's birthday honours list.
"I've led a wonderful life and have had a tremendous career thanks to the generous support of the great British public," he said. "This monumental honour has topped it off and I couldn't ask for anything more. I thank Her Majesty and promise to wear it well."