The Fuller House star and his new fiancee turned out for a benefit dinner hosted by mothers2mothers and The Elizabeth Taylor AIDS Foundation at Ron Burkle’s Green Acres Estate in Beverly Hills, California, on Tuesday, where he spoke with ET about popping the question on Sunday.
"I didn’t even walk in. Did you see? I just floated from the car," Stamos said, beaming. "I’m on cloud nine. I’ve been waiting for the perfect girl for over a decade and she walked into my life."
Stamos took to Instagram on Sunday to share the special engagement news, posting an illustration of him and McHugh standing in front of Disneyland's Sleeping Beauty Castle, as fireworks burst in the air.
"I asked...she said yes! ...And we lived happily ever after," Stamos captioned the pic, along with an engagement ring emoji.
The 54-year-old sitcom star told ET that he's "always loved family and wanted to have a family someday," but before he could find love and get married again, he needed to do some work on improving himself.
"A true, pure, beautiful person inside would have never gone for the old me a few years ago," Stamos said. "I had to get to the best me. Get back to the person I was, hit reset, and then I knew the right person would come along. Especially if I prayed and hoped and I knew my parents were up there watching. So I think they delivered an angel to me."
"We're a perfect balance. I'm like, hyper and tense and she's like, 'It's cool man. Everything's fine,' Stamos said of his ladylove. "She's so calm and so graceful, which I'm not either of those things, so it's just a great balance. She's just a pure, authentic beauty. She's not trying to be something she isn't. She doesn't care about money or showbiz."
As for the star's picture-perfect Fantasyland proposal, the Scream Queens actor said he got some advice from Disney CEO Bob Iger himself.
"[Iger] happened to email me like a month or so ago, and it was like, the funniest email early in the morning, like, 'Hey, I follow you and Caitlin on Instagram and she's really a Disney geek, isn't she?'" Stamos recalled, referring to his fiancee's active involvement in Disneybounding -- a hobby among some Disney enthusiasts, who dress up in modern clothing ensembles influenced by specific Disney characters.
The actor used the opportunity to ask the studio head for some pointers on how to make the proposal even more romantic.
"So he got involved, and then I got a Disney animator friend of mine, Paul Briggs, and he helped me cut together a little movie of all the most romantic moments [from] Disney/Pixar animation, and it was pretty special," the star explained.
From top to bottom, Stamos said he handled the entire proposal without McHugh knowing -- including picking out the engagement ring. And he certainly got something very special from famed jeweler Neil Lane.
"It's from 1945," he shared. "[It's an] old, vintage ring, and I just know her and [it] worked."
"They all love her more than me. They're like, 'Is Caitlin coming?'" he joked to ET. "'We don't care about you, is Caitlin coming?'" Check out the video below to hear more about Stamos' adorable Disneyland proposal.