The "Uptown Funk" hitmaker announced the exciting news on the latest instalment of his podcast "The Fader Uncovered" during a chat with fellow musician, Tame Impala's Kevin Parker.
"I got engaged last weekend," he beamed. "And I remember our first kiss... (Tame Impala album) InnerSpeaker was playing in the background. We go home, we went to dinner..."
"Congrats man," interrupted Parker. "Congrats on InnerSpeaker playing in the background. No, I'm just joking. Yeah. Congrats."
Ronson added that, while his first kiss with his fiancee was "corny," he'll remember it forever.
"There's a plaque for that somewhere. There's a first kiss, very corny hallmark first kiss plaque," he joked. "But no, it was forever, it will be etched. It's still my record."
Rumours had been swirling the couple planned to wed after the duo was spotted out on a dinner date in May (21), with Grace rocking a large diamond on her left ring finger.
The engagement news comes 10 months after Grace, the daughter of Meryl Streep and Don Gummer, finalised her divorce from Tay Strathairn.
Meanwhile, Ronson's 2011 marriage to French actress and singer Josephine de La Baume officially ended in 2018.
He previously said he turned to therapy as his marriage fell apart, "I was kind of directionless. It sounds a bit spiritual or abstract, but when I think about myself then, I wasn't even in my body."
"It was like this thing when you're out of this long relationship there's this tendency to go, 'Well, the last two years were really tough, so I am going to drink and have fun and do whatever I want.' Obviously, it wasn't a super-helpful way to deal with it."