The 4 Non Blondes rocker, who has penned hits for Pink and Christina Aguilera, began dating the former Roseanne star in 2011 and now the couple is set to wed after Perry proposed over a picnic in Los Angeles.
Announcing the news while co-hosting her U.S. show The Talk on Monday (08Apr13), Gilbert said, "We go to a park, and we have food and we're eating it, it's really sweet and there's this guy sitting playing guitar, like a street musician, and he starts playing this song that we love... I'm like, 'Oh, that's so weird, this is so magical and amazing.'
"So that ends and she's like, 'Oh, I'm gonna ask him to play this other song,' but this other song is really obscure and this guy wouldn't know it, but magically he knows it... And suddenly the people picnicking next to us pull out string instruments from under the blanket and walk over and they start playing Love Song (by the Cure)...
"Then she goes to her backpack and she pulls out some T-shirts and the first T-shirt says, 'Will,' and then she puts on another T-Shirt that says, 'You,' Marry, Me and the last one is a question mark. And then she goes to her backpack and gets a ring."
And Perry even called on her pal John Waite for a surprise private performance of "their" song, Missing You.
She adds, "So then she says, 'Ok, turn around,' and I turn around and our mums are there and a couple friends... So I think that's it and it's the most amazing proposal ever and then... this guy walks up and she's like, 'This is John Waite,' and he starts playing Missing You."