The news breaks as reports emerged that WPP is talking to AdPeople about a possible acquisition. The Copenhagen-based full-service agency also has an outpost in Bangladesh.
The lion's share of Dell's advertising is in press, which is now moving to AdPeople from DDB. However, DDB will keep the TV account.
AdPeople already handles Dell's online and direct marketing.
Ronnie Job, the founder of Adpeople, refused to comment on the Dell appointment.
However, he confirmed talks were taking place with WPP. He said a deal would only be struck if it enabled the agency to improve the level of service it could offer clients. WPP declined to comment.
Dell's move follows a downbeat set of financial results. Last month, the computer giant reported first-quarter figures for 2006 that showed a 19 per cent fall in operating income to £502 million.
DDB's London office is also experiencing difficult times. It has been without a chief executive since the beginning of the year and has lost its PG Tips, Guardian and Weetabix accounts in that period.