The move will see Weber Shandwick act as a 'hub' for all local markets in EMEA, with the business believed to be worth about £1m a year.
A spokesman for Microsoft said: 'In seeking an agency, we wanted to reinvigorate the Windows brand - it is much more than an operating system - and create a passion for Microsoft's consumer products. We were looking for a creative agency with a strong footprint across Europe to help us to do this.'
The move comes weeks after Waggener Edstrom won the global brief for Microsoft's mobile comms business, taking over from Weber Shandwick (PRWeek, 15 May). In January, the UK consumer and online account was awarded to 3 Monkeys.
The pitches are understood to have been driven by head of international PR Oliver Roll, who joined last year.
Weber Shandwick's pan-EMEA brief is in addition to the agency's current brief for all non-consumer Microsoft PR across EMEA, including corporate and tech, which it has held since last September.
The online part of the account was previously held by The Red Consultancy. It has now been incorporated in a newly created pan-EMEA consumer and online division.
The new brief includes Microsoft's PC, phone and web businesses.