The switch to the Berliner format, which was adopted by The Guardian in September, will see the paper relaunched with a redesign of all its newsprint sections and magazines.
It will also see the introduction of the fourth monthly magazine, Observer Woman, which was announced earlier this month.
Roger Alton, editor of The Observer, said: "Sundays have changed dramatically over recent years and the Berliner Observer will be the most modern, punchy, engaging Sunday paper, with more variety for the reader, more interactivity with our audience, fantastic use of pictures, a brilliant stable of writers and the best array of magazines in the market."
The redesign includes a full-colour main news section and a new 7 Days news features section; Business & Media has been combined with Cash to create a comprehensive Sunday business and personal finance section; and the Review, Sport and Escape sections have all received Berliner-sized full-colour makeovers.
The Observer Magazine has been redesigned alongside a new, separate half-Berliner TV listings guide.
In addition, the comedy writer and producer Armando Iannucci will join the paper to write a new weekly column
Carolyn McCall, chief executive of Guardian Newspapers, said: "The Berliner format has already proved a huge success with the Guardian's readers and advertisers, uniquely combining ease of reading with editorial integrity, and we have every confidence it will prove a long-term winner for The Observer as well."
In the most recent set of ABCs, The Observer sank by just under 15,000 copies, or 3.3%, to 435,882, while sister paper The Guardian has failed to enjoy a sustained lift in sales from its switch to Berliner format and management have been attacked for the way the relaunch was handled.
On Friday Albert Scardino, a former senior editor at The Guardian, launched a broadside at the paper's senior management, saying they are a failure and have "no idea" how to take advantage of its journalistic success.
Scardino questioned the circulation performance of The Guardian since its relaunch.
"Journalistically, the paper is one of the most successful of its generation. But the commercial and managerial sides of The Guardian are a failure by any meaningful performance benchmark," he said.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .
.jpg)
.jpg)