News UK, Murdoch's UK-based publishing house, announced plans to scrap the paywall and offer most of its website content for free.
News UK chief executive Rebekah Brooks informed staff yesterday of the new strategy, which will kick off from November 30.
"I recently shared with you the future priorities for the company and am excited today to tell you more about our plans for the first of these growing The Sun's audience.
News UK had made the decision to put the UK's biggest- selling tabloid behind a paywall in August 2013, following a decision to move its other titles - the Times and the Sunday Times - on to a paid service.
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Brooks described this as a "new chapter for The Sun", which she had put behind the paywall before her high-profile exit from the publishing house amid the phone hacking scandal in 2011.
The entry of 'The Sun' to the free digital ad market marks a major ramping-up of competition among national British newspapers in the battle for digital advertising pounds in a market dominated by US giants Google and Facebook.