The band, consisting of twin brothers Matt and Luke Goss, recalled the moment they met the "gentle and kind" princess.
"It was one of the most incredible moments, she's one of those ladies that's just full of love and she had these piercing blue eyes that just made you blush in the best way and she knew it," the brothers said during an appearance on The Jonathan Ross Show.
"She had these piercing blue eyes that just made you blush," said the brothers
"She was so gentle and kind and beautiful and I don't think there was a man on Earth who could not be affected by her," they added.
"I had a huge crush on her when I met her," Luke admitted. "I just thought wow, beautiful, beautiful lady."
The band split in 1992 after being "sick of the sight of each other" and needing to discover who they were as individuals.
Matt and Luke Goss have reunited without former bandmate Craig Logan
Matt and Luke recently announced that they are reuniting for their 30th anniversary tour, but without their former bandmate Craig Logan.
"We didn't [offer him to come back] quite simply," said Matt. "To be honest with you, me and my brother started the band when we were kids and at Wembley Stadium in 1977, a thousand people turned up to that show. That was just me and my brother. He left the band and we decided Bros means brothers and that's who's playing the O2."
"We're going to be very faithful to the sound of the band," said Luke
Fans can expect to see the 48-year-old brothers "let our hair down" and "have a lot of fun" at their comeback. They'll be singing their hits and tunes from their first album.
"We're going to be very faithful to the sound of the band," said Luke.
Matt added: "We're obsessed with technology so we want the show to be very contemporary but there are things from back in the day that work as well so we're going to take both into consideration."