The figure, reported in the latest results from the Audit Bureau of Circulation, represents a 58 per cent year-on-year traffic increase for the site, which has been Britain's highest-traffic news site for the past 13 months consecutively.
According to Associated Newspapers, which publishes the Daily Mail, Mail on Sunday and Mail Online, just 27.8 million of its monthly unique browsers come from the UK.
In terms of traffic, Mail Online is the second largest English-language news website in the world, after the New York Times site.
The Guardian was the second most popular site, with an average of 3.3 million users per day, compared with Mail Online's 4.6 million. The Guardian didn't report a monthly figure.
The Telegraph was the second highest traffic site, averaging 2,292,052 unique browsers a day and 45,310,524 for the month."