The 27-year-old singer tied the knot with former World Superbike champion James Toseland in a lavish ceremony at the Nash Conservatory at the Royal Botanic Gardens in Kew, London.
Among the 200 wedding guests were music producer William Orbit and composer Mike Batt as well as Prince Pieter-Christiaan Michiel of the Netherlands.
The `Nine Million Bicycles` singer wore an off-white beaded dress by bridal designer Claire Pettibone, her spokeswoman has confirmed.
Katie and James have been together since April 2011 after meeting at one of her concerts in Sheffield, North England.
The pair got engaged in January after the former MotoGP star - who quit the sport in September 2011 after breaking both his wrists - proposed.
He wrote on his Facebook page at the time: "I asked Katie to marry me and she said yes. As you can imagine, I am a very happy man right now!"
Katie is one of the biggest-selling British female artists of all time after being discovered in 2002 while studying at the Brit School for Performing Arts, which counts Adele, Jessie J and Amy Winehouse among its former pupils.
The singer - who suffered a nervous breakdown two years ago - recently confessed that she hasn`t always believed in marriage, but meeting James changed her mind.
She said: "Marriage seemed so scary then. But once you have met the right person..."