Microsoft chief Steve Ballmer, who will step down within a year, acknowledged that the firm was too slow to respond to opportunities in the smartphone market.
Ballmer regretted that there was a period in the early 2000s when the company was so focused on what it had to do around Windows that it missed opportunities in the mobile market.
"That is thing I regret the most," Ballmer said.
"It would have been better for Windows and our success in other foreign factors."
However, the US PC maker claims that it still has major opportunities in the market, and believes that the recent acquisition of the Nokia's mobile phone unit would speed up the development on its Windows Phone platform.
"We must do the work to ensure that the PC stays the device of choice when they're trying to be productive in life," Ballmer added.
"We have the tools. There's economic upside here. In the long run, we are almost uniquely poised to seize the opportunity."
The US software giant has come under fire recently for not responding to the way Apple and Google have led the way in mobile devices and has struggled to sustain sales as consumers were in support of tablets over PCs.
Android dominated the list of the smartphone operating systems, followed by iOS, Windows Phone and BlackBerry OS.
In 2013, global smartphone shipments are expected to report 40% rise to over 1.0 billion units, with the number reaching 1.7 billion units in 2017.