Microsoft's Office for iPad suite of apps has been downloaded more than 12 million times since its officially launch last week.
News of the milestone was broken by Microsoft's Twitter handle @Office.
Microsoft Word, Excel, and PowerPoint now occupy the top three spots on the App Store's free app charts, having racked up downloads since their arrival on iPad one week ago.
The apps let users read Office documents for free, though creating and editing content requires an Office 365 subscription.
Office 365 costs $99 per year for five licenses or $69 per year for an individual subscription.
Subscribers can access Office through desktop apps, a web editor, and now native Android and iPad apps.
Microsoft has not said how many users have paid for an Office 365 subscription through the new apps.
At the time of writing, Word and Excel are the 13th- and 21st-highest-grossing apps on the App Store. All subscriptions within Office for iPad are subject to Apple's usual 30 per cent tax, making Office into a cash cow for Cupertino as well.
The release shows a shift in Microsoft's strategy for delivering its content. The company had previously kept Office away from Apple's mobile platform to push Windows.
"What motivates us is the realities of our customers," said CEO Satya Nadella during the launch of Office for iPad last week.
"We live in a world where device types, shapes, sizes and form factors are exploding and will continue to do so," he wrote in a blog post afterwards. "We are fully committed to offering market-leading productivity solutions across all popular platforms and devices."
Nadella has moved Microsoft's focus to being "mobile-first, cloud-first," reflecting his extensive background in the field.
