Mainstream co-founder Bill Campbell has said the decision to cease forward publishing represents a "planned exit" for himself and co-founder Peter MacKenzie and is not a result of tough trading conditions.
"We came into this 35 years ago—a lifetime—and we've got other things we want to do," he said. "It's a planned and phased exit, we're not disappearing overnight."
He added: "We're a profitable company. Sure, there are considerations, there are always considerations—but we'd a healthy profit last year and we intend to have a great year again. It's not of necessity, it's of will. We've decided we want to complete the circle together."
Campbell declined to give details of any next steps planned for himself or MacKenzie.
The Edinburgh office of the Scottish independent will close on 31st December, with the loss of all 10 staff jobs.
The company will publish all of its already scheduled titles, with the final title to be published in March 2014. Its backlist, which includes titles by Carol Ann Lee, Hugh McIlvanney and Warren Fellowes, will continue to be published as an imprint within the Random House Group.
Campbell described it as "an active and dynamic backlist".
Nick Barley, director of the Edinburgh International Book Fair, called Mainstream's closure a "sad loss to Scottish publishing."