Northern Irishman Mr Rea, 30, who recently added the 2017 title to those he won in 2016 and 2015, said they talked about motorbikes during the ceremony at Buckingham Palace.
The father-of-two told the Press Association it had been an honour to receive an accolade outside the sport, before adding: “I know he’s a bit of a motorcycle fan himself.
“We talked about his bikes and the fact that he has put it on the back-burner a little bit because of his children now.”
Along with his brother Prince Harry, the Duke has been a keen biker from a young age and had previously been known to own bikes including a 1199cc Ducati.
In 2008 the brothers previously took part in an arduous motorcycle rally across Africa to raise money for a variety of charities including Sentebale, which was jointly founded by Prince Harry.