Microsoft said the functionality would be included in the next updates to the Office mobile apps, to be rolled out in the next few weeks, and online accessibility would be available in the first half of 2015.
Microsoft already has a file-sharing service called OneDrive, but partnering with Dropbox will allow it to tap more than 200 million users of the Silicon Valley startup's services.

Microsoft announces 'Windows 10' operating system

Microsoft Corp  announced its 'Windows 10' operating system on Tuesday to replace the largely unpopular Windows 8, skipping a number to mark a leap toward unifying the way people work on tablets, phones and traditional computers.

The next version of Microsoft's flagship product, which still runs the vast majority of personal computers and is used by 1.5 billion customers worldwide, is aimed at recapturing the lucrative business market, which generally ignored the new-look Windows 8.
Windows 10 will be "our greatest enterprise platform ever," said Terry Myerson, Microsoft's head of operating systems, at an event in San Francisco. Only 20 percent of organizations migrated to Windows 8, which was released two years ago, according to tech research firm Forrester. Many PC users disliked the touch-optimized interface and bemoaned the loss of the traditional start-button pop-up menu.
He said Windows 10, long known by the project name 'Threshold' internally, represented a new type of system for the company, as it seeks to unify computing as mobile devices proliferate. The name represented that leap, he said.
"Windows 10 adapts to the devices customers are using, from Xbox to PCs and phones to tablets and tiny gadgets," said Myerson.
Microsoft faces an uphill struggle in reigniting excitement about Windows. With the rise of Apple Inc's iPhone and iPad, and Google Inc's Android devices, Windows no longer plays a central role in many people's on-screen lives.
From a virtual monopoly on personal computing 10 years ago, Windows now runs only about 14 percent of devices, according to research firm Gartner.