The Spice Girl, 47, will marry for the third time after the hairdresser, 34, got down on one knee at the luxury five-star country house Cliveden Hotel in Berkshire.
She revealed it was very romantic as there were lots of rose petals everywhere as she “loves flowers”.
Mum-of-three Mel made the admission during an appearance on Celebrity Gogglebox on Friday night.
Getting her to dish the dirt, Ruby asked Mel: “You told me you got engaged the other day. What did he actually say?”
Get all the biggest showbiz news straight to your inbox. Sign up for the free Mirror Showbiz newsletter.
A smitten Mel replied: “He said ‘I love you, you’re my best friend and I want to spend the rest of my life with you’.”
The pop star added: “There were rose petals everywhere, a log fire, a hotel - which was Cliveden. It was very romantic. I love flowers.”
Mel, who is best known as Scary Spice, is said to have “burst into tears” when her beau of around four years popped the question.
Rory got down on one knee with a £100,000 champagne-coloured diamond ring when they stayed in the hotel last week.
Mel has been married twice before. First to dancer Jimmy Gulzar, who she shares eldest daughter Phoenix Chi, now 23, with.
Her second marriage was to US TV producer Stephen Belafonte, which lasted 10 years and Mel claims was physically and emotionally abusive. They have an 11-year-old daughter called Madison together.
She also has 15-year-old daughter Angel with actor Eddie Murphy.
Mel was reportedly “overwhelmed” by the proposal and immediately said yes.
A source told The Sun that hairdresser Rory, who is from Leeds like Mel, has restored her trust in men.
"Mel is so happy and this is such a big deal for her because she has been though such a lot,” they said.
“He’s the absolute opposite of so many guys she has had relationships with. he has really taken the time to understand what she’s been through. He is madly in love with her.”
The insider added Rory - who is said to be close friends with her cousin, actor Christian Cooke - has got her to "believe in love again" following past experiences.
Rory is described as a “down-to-earth guy” who isn’t interested in fame and has worked “incredibly hard” to build up his own business.
But finding love hasn’t always been easy for Mel, who has spoken out about her abusive 10-year marriage to US TV producer Stephen Belafonte.
Stephen has always denied the allegations and the couple divorced in 2017.
Speaking earlier this year, she said she was in an “emotionally and physically abusive marriage” for a decade, which was so bad she can barely remember what happened to her because of post-abuse trauma, which can “last a lifetime”.
“Nearly five years on I still wake up in the early hours with terrifying fragments of sounds and images flitting into my brain,” Mel said, admitting that some nights she wakes up “drenched in shame, sweat and fear”.
Mel became a patron for domestic violence survivors' charity, Women's Aid, in November 2018 and was later awarded an MBE for her work helping other women suffering domestic abuse.
Do you have a story to sell? Get in touch with us at email@example.com or call us direct 0207 29 33033