Staff at both newspapers were told last month that merger talks were taking place, and a deal has now been signed in Edinburgh.
In a statement, the company said both newspapers would continue to be published independently and have their own editors and reporting staff.
However, HoldtheFrontPage understands that a review of operations will take place.
James and Christine Miller, previously owners of The Orcadian Limited, own 50 per cent of Orkney Media Group Limited, and S & JD Robertson Group – previously owners of Orkney Today – own the other half.
The directors of Orkney Media Group are James Miller and Christine Miller, John Robertson and Sinclair Robertson, who has been appointed managing director.
John Robertson and James Miller are be joint chairmen.
The Orcadian is Orkney’s long-established newspaper, founded in 1854 by James Urquhart Anderson. James Miller is Anderson’s great, great, great grandson.
It has a circulation of 10,256.
Orkney Today was launched in 2003, giving the island a second weekly paper for the first time in 40 years, and sells 6,518 copies a week.
Both newspapers are published on a Thursday and are based in separate offices in Kirkwall.