Scott, who has been named director of global agencies, will be given the task of setting up a division in Seattle to cut ad deals between Microsoft and agency networks, such as WPP Group, Omnicom, Publicis, Havas and Aegis.
Scott, who begins his new role next month, will oversee Microsoft media products that carry advertising, such as the Xbox Live online gaming network, gaming websites, MSN websites and Hotmail.
He left Ninemsn, the joint venture between PBL Media and Microsoft, in July after five years at the company. Ninemsn effectively acts as the website for both the Nine Network and MSN in Australia.
Before joining Ninemsn, Scott worked as general manager for Australia and New Zealand at interactive media agency NetX.
His appointment at Microsoft comes as the software giant continues to aggressively expand into the ad business.