Opera Unite allows users to stream music or share files, photos and more via the web browser.
Opera said the new download rate "shatters previous Opera records" and shows a 25 percent increase on the number of downloads of Opera 10 when it was launched earlier in the year without the Unite technology included.
"With such remarkable download numbers, I am confident that we truly appealed to the needs of the web-using public," said Jon von Tetzchner, CEO, Opera Software.
"Opera 10.10 is visually more compelling, and technologically speaking, it goes where no browser has gone before. We believe that, over time, Opera Unite has the power to erase preconceptions of how we access and share information on the web."
See also: Opera Mini use surges 11 percent