The business was previously handled by Media Planning Group. The company has spent £4 million during the past 12 months, but is expected to more than double its investment .
PHD won the account after a pitch process handled by the AAR. Online media buying will remain with MPG, through its Media Contacts division.
Beverly Shaw, the marketing director for expedia. co.uk, said: "It's great to welcome PHD on board at what is an important stage in Expedia's brand development in the UK. The agency has demonstrated that it understands the issues and opportunities surrounding our business and that it has both the strategic thinking and creative ideas to continue moving the brand forward."
Daren Rubins, the group media director at PHD, added: "We are excited about using all of the PHD group companies to help develop Expedia into new marketing territories. Expedia has every right to expect the same creativity in its media planning and buying as it gains from its advertising."
The appointment will be effective from January.