Online design and publishing platform Canva has become the first Australian start-up since Atlassian to join the elite ranks of Silicon Valley unicorns with a valuation in excess of $US1 billion ($1.28 billion).

The valuation is based on a $US40 million series A funding round. It is the sixth funding round since the company was founded 4½ years ago by Melanie Perkins, Cliff Obrecht and Cameron Adams.