Boyfriend Jamie Hince reportedly popped the question on Tuesday night, with a beautiful vintage 1920s ring to hand.
The pair were spotted celebrating at Ceccone's restaurant in London yesterday, while bunches of flowers have started arriving at their new home in Hampstead.
One source told The Sun: 'Kate is delighted. Jamie is the man for her - they are soul mates.
'They're going to have the mother of all weddings. It will be a huge party, one of the biggest she has ever thrown - and she's thrown a few.'
But the big question now, of course, is - who will design her wedding dress?
See more beautiful celebrity engagement rings.