MPG's first task is to handle the launch of Pioneer's latest range of plasma televisions with a multimedia campaign running across the autumn.
The agency claimed the campaign spend will be £5 million.
Pioneer has previously used Universal McCann Birmingham for its UK planning and buying, but its spend so far this year has been less than £1 million.
It appointed MPG after a pitch process.
Heidi Johnson-Cash, Pioneer GB's marketing manager, said: "MPG is keen and knowledgeable, its media plans are innovative and we are looking forward to working with the agency."
Creative for the Plasma campaign will be adapted in-house from overseas work.
The Japan-based Pioneer makes electronics products covering in-car, hi-fi, DVD, TV, computer and business.