Mozilla's Firefox 4 browser surpassed 100 million downloads over the weekend, and more than 105 million copies of the browser had been distributed by Monday evening US time.
More than 40 million downloads have been served to systems in Europe, followed by 30 million in North America and 20 million in Asia.
The milestone comes a little more than a month after the final versions of the browser were released. Firefox 4 was an early hit with consumers, and had passed the 50 million download mark by early April.
Mozilla's director of community development, Asa Dotzler, suggested that Firefox 4 could see a further surge in downloads as distribution is expanded.
"If all goes according to plan, we'll be letting Firefox 3.5 and 3.6 users know about Firefox 4 with that 'advertised' or 'prompted' update in about 10 days," Dotzler wrote in a blog post.
"I'll bet we see a nice uptick in the Firefox 4 trend when we actually start to communicate its availability to users of older Firefox versions."
The rise of Firefox 4 comes as the browser's top target, Microsoft's Internet Explorer 9, has lagged in its early adoption.
Many analysts have suggested that strategic decisions, such as the exclusion of Windows XP support in IE9, could reflect a broader long-term strategy for Microsoft.