Carfrae, 32, won her second title in a time of eight hours 52 minutes 14 seconds, breaking Briton Chrissie Wellington's course record of 8:54:02.
Joyce was second in 8:57:28, with Blatchford (9:03:35) third and defending champion Leanda Cave 13th.
The event comprises a 2.4-mile swim, a 112-mile cycle and a 26.2-mile run.
Carfrae, also champion in 2010, said: "I just had one of those days where you don't hurt - I didn't know I had a performance like that in me."
British competitors had won the race in five of the previous six years, four by Wellington.
Joyce, 35, said: "I gave everything and when you do that, you can't ask for any more."
Compatriot Jodie Swallow did not finish.
The men's race was won by Belgium's Frederik Van Lierde in 8:12:29 - the eighth-fastest time in the 35-year history of the event.
"I tried to be smart and it worked out," said Van Lierde, who was third in 2012.
"After last year, I believed I could do it. I worked hard this year. This is amazing."
Britons Rachel Joyce and Liz Blatchford were second and third respectively as Australia's Mirinda Carfrae won the Ironman World Championship in Hawaii.