The judging panel was made up of Amber Peebles, Tracey Dalton, Georgia Connolly and Janetta Mackay.
Head judge Mackay praised Carson's style, saying: "She used her imagination to combine high street fashion with a twist of couture.
"Her hair, makeup and overall finish was impeccable. We were really impressed.''
Carson receives a prize pack worth more than $20,000 and includes a trip to this year's Melbourne Cup Carnival.
She will represent New Zealand in the Fashions on the Field competition there.
Today's Viva Prix de Fashion contest was held at the Shakespeare Pop Up Globe theatre in Ellerslie - providing an impressive backdrop to the event.