The company's 1,500 staff were briefed on the strategy today by editor-in-chief Alan Rusbridger and Andrew Miller, the chief executive of parent company Guardian News & Media.
No redundancy programme has yet started but is expected given the extent of the savings required to reduce what is understood to be an operating loss of approximately £35m in the company's last financial year (to the end of March).
Revenues have dropped by 10% to approximately £200m, in large part due to the loss of print recruitment advertising income.
The cost-savings are designed to reduce operating losses to a "sustainable level" of £15m by 2015-16, but are unlikely to result in an immediate reduction.
Savings will be focused on print and a review of processes across the business.
While the company claims print remains "critical", Rusbridger said: "Every newspaper is on a journey into some kind of digital future. That doesn't mean getting out of print, but it does require a greater focus of attention, imagination and resource on the various forms that digital future is likely to take."
The first changes in the "digital-first" strategy will come on the weekday Guardian. At a later date the Saturday Guardian and The Observer will also be reviewed. No timescale has been given but mock-ups are believed to be circulating internally.
The changes are expected to make the paper less focused on news and more on analysis, but it is not clear how many pages will be cut or what will happen to its supplements, such as Education Guardian and Society Guardian.
Rusbridger said: "Half our readers now read the paper in the evening. They get their breaking news from our website or on mobile."
GNM's website output will remain free and Miller remains opposed to introducing a paywall. However, he has ambitions to increase subscriptions with new combined print and digital offerings, understood to include an in-development iPad app for The Guardian.
The company wants to grow digital revenues from their £35m-£40m level in 2010/11 to £90m in five years' time.