Mail Online, which has reported record figures for several months, had an unprecedented 3.04m average daily unique browsers, up 3.58% on November 2010.
The Guardian, ranking second, was down 3.9% from November with an average of 2.23m average daily unique browsers.
Its nearest rival, The Telegraph, also experienced a dip in average daily unique browsers, down 8.17% to 1.58m in December.
The Independent’s readership fell 9.9% to 504,507 average daily unique browsers.
Mirror.co.uk had an average daily unique browser total to 503,959 for December, down 5.6%.
The fortunes are in contrast to that of the newsprint editions, which all saw a drop in December, according to ABC figures.
This story first appeared on newmediaage.co.uk