IPM has handled the BSkyB account for six years and was reappointed following a detailed review process and a renegotiation of terms in view of current market conditions.
According to The Nielsen Company, BSkyB spent £15.9m on outdoor media in the year to 31 May.
Steve Beckett, head of media at BSkyB, said IPM had delivered "consistently outstanding" outdoor planning and buying.
He said: "BSkyB wanted to make a public statement about the quality of IPM's performance and about its role as a key partner of ours over the next few years.
"We look forward to a continued long and fruitful relationship."
Roy Jeans, chief executive at IPM, said: "IPM is really pleased to be able to start planning for long-term activity for BSkyB. This deal takes us up to 2012 and the retention is an indication of the excellence of planning and buying work we do."
IPM is a wholly owned subsidiary of The Interpublic Group and handles out-of-home media for Interpublic media agencies Universal McCann and Initiative.
In 2008, IPM's billings totalled just under £85m.
Moving forward, IPM expects about 55% of its business to come from direct clients, which include Samsung and Intel.