More than 200 events are expected to unite for 24 hours during the final countdown to the landmark anniversary of the Edinburgh Festival Fringe.
The 1947 origins of the event, which was instigated by artists and companies who were not invited to take part in the first ever Edinburgh International Festival, will be celebrated as far afield as Canada, Australia and South Africa.
The one-day campaign, which is being backed to the tune of Â£100,000 by the Scottish Government, is expected to see special events staged in participating cities, with messages of goodwill sent to Edinburgh across the world.
Performers, producers, venues and festival-goers will be urged to take part in a social media drive aimed at spreading “the collective power and worldwide reach of Fringe movement.”
It is hoped the initiative, which will only involve "open access" festivals, will emulate the kind of online buzz generated by St Patrick's Day and Burns Day each year.
World Fringe Day will be stage less than a month before the annual Edinburgh event gets underway and will highlight the city's role as the "birthplace" of the worldwide Fringe movement.
Organisers of World Fringe Day, which will be held on 11 July, say the international celebration will “transcend national boundaries, demonstrating the power of arts and culture to bring people together.”
World Fringe Day was launched in Edinburgh today by Scottish culture secretary Fiona Hyslop and Fringe chief executive Shona McCarthy. They also unveiled a an open-top bus which has specially branded to celebrate the Fringe 70th anniversary and will be part of the 30-strong Edinburgh Bus Tours fleet.
Ms McCarthy said: "We're thrilled to reveal the plans for the first ever World Fringe Day.
"We can’t wait to join with our sister Fringes across the world to celebrate the wonder and joy of fringe festivals in this auspicious year.
"This is an incredible opportunity for Fringe organisers, venues, participants and audiences to take part in a truly international celebration of creativity that will transcend national boundaries, demonstrating the power of arts and culture to bring people together.
We hope as many people as possible will join us for a very special day of worldwide fringe fun, as we celebrate 70 years of Fringe and pay homage to Scotland as the birthplace of the Fringe movement.”
Ms Hyslop said: "World Fringe Day is a fantastic opportunity to celebrate the global connections that Scotland has made through the arts. Edinburgh’s festivals are world renowned and it is remarkable to think that the fringe movement, that began here in 1947 with the founding of the Edinburgh Festival Fringe, has developed into a worldwide network with Fringes now taking place on every continent except Antarctica.
"The Scottish Government is proud to support World Fringe Day, acknowledging Scotland as the home of fringe and joining with the many other wonderful fringe festivals around the world for an international day of celebration."