Mirror.co.uk, which includes data journalism site Ampp3d and new football offering Mirror Row Zed, received 64.9 million unique browsers in July up from 50.7 million in June.
The outlet also saw a 118 per cent rise in web traffic year-on-year, a percentage increase beaten only by Metro, which has seen constantly high year-on-year on growth since adopting a mobile-first strategy at the end of 2012.
Pete Picton, editor of Mirror Online, credited the growth in part to how content was being delivered to audiences across different platforms and "seamless" work between editorial and technology departments.
"Mobile and video are performing really well for us," he told Journalism.co.uk by email, "as is the way we are utilising our social media channels – recently we passed a million likes on Facebook."
There were traffic increases across the board for all audited news sites except The Telegraph, which experienced a slight (3 per cent) drop.
Other notable month-on-month increases include The Daily Express and the Daily Star, up 23.7 per cent to 16.6 million browsers and and 21.2 per cent to 10.9 million browsers respectively.
Both outlets have seen consistent growth in traffic since beginning to include figures in ABC's multiplatform report in February of this year.
Meanwhile, traffic to Metro rose by 15.5 per cent to 33.7 million browsers, and The Independent was up 10.7 per cent to 44.3 million browsers.
The Guardian also reported a 5.1 per cent increase, one year after moving to its new domain theguardian.com, while traffic to Mail Online – still the largest audited news site with 174.6 million uniques in July – rose by 3.8 per cent.
Additional reporting by Alastair Reid