An estimated one and a half million people gathered at Sydney Harbor, event organizers said.
Organizers estimate that the pyrotechnics display, which cost A$6.8m ($6.06m), would be watched by as many as a billion people around the world.
Meanwhile, hundreds of Japanese revelers welcomed 2015 by letting hundreds of balloons go flying up into the air in front of Tokyo Tower.
Counting down to the New Year, and as Tokyo Tower changed its display from 2014 to 2015, guests who had gathered at the Tokyo Prince Park Hotel said they wanted 2015 to be an exciting year.