The 23-year-old singer, who grew up on the Gold Coast, performed his song Not the Same wearing a crystal mask and a flamboyant white outfit that sported about 180,000 crystals.
Australia was one of 18 performers in the second semi-final on Thursday night and joins Belgium, Czech Republic, Azerbaijan, Poland, Finland, Estonia, Sweden, Romania and Serbia in moving to the decider on Saturday night (Sunday morning AEST).
They will join the 10 successful countries from the first semi-final, including Ukraine, Norway, Switzerland, Armenia, Iceland, Lithuania, Portugal, Greece, Moldova and the Netherlands.
The UK, Spain, Germany, France and Italy don't have to qualify from the semi-final stage and gain automatic access to the final.
Eurovision organisers later announced that Riley would perform in the second half of Saturday's show.
Ukrainian act Kalush Orchestra are considered the favourites to win this year's contest.