The 23-year-old singer/songwriter has claimed the 'Juice' hitmaker, 31, told him he's "hot" as she left the bash in London after the ceremony in February.
He told The Sun newspaper's Bizarre column: “I bumped into Lizzo, which was one of the best things that’s ever happened to me.
“It was about 3am and she was like, ‘You’re hot’, as she was walking out.
“I walked in with the biggest smile on my face that any man has ever had.”
The 'Lying That You Love Me’ singer was out partying with pal Lewis Capaldi, who had just won two awards for New Artist and British Single for 'Someone You Loved'.
JC also shared how when he and the Scottish star first met at a party in Los Angeles, the cops came out and started ID'ing everyone.
He recalled: “We met at a house party in LA about three years ago.
“At the end of the party me and Lewis were sitting upstairs and I got a text from a friend of mine and he was like, ‘You’ve got to get out of here now, the police are downstairs’.
“I walked down and there were cops at the door checking people’s IDs, so I snuck out.”
Meanwhile, at the BRITs ceremony at The O2 arena, Lizzo and Harry Styles showed how much they love each other.
When the US pop superstar was asked about the 'Falling' singer during an interview with host Jack Whitehall, Lizzo tapped the former One Direction star on the shoulder, before they shared a hug.
Harry was then seemingly drinking a wine glass of neat tequila and Lizzo sipped it to see if it was in fact the spirit, before downing it in one, much to the delight of the ‘Watermelon Sugar’ hitmaker.
The pair had previously duetted on 'Juice' together at the pre-Super Bowl gig in Miami.