An Enfatico spokesman said the move was a "strategic decision" that allows Enfatico "to tap Y&R's available resources for Dell and other clients".
Torrence Boone, chief executive of Enfatico, will now report to Y&R Brands chief executive Peter Stringham instead of WPP chief executive Sir Martin Sorrell.
The agency, created by WPP to win a holding company pitch for Dell's global account at the end of 2007, had failed to secure any other client until landing Progress Software last week according to reports.
The strength of Dell's relationship with Enfatico was also thrown into doubt by the departures in 2008 of the two senior Dell marketers, Mark Jarvis and Casey Jones, who spearheaded the agency's creation to reduce their company's vast worldwide roster of marketing agencies.
Enfatico made around 80 people redundant, accounting for 8% of its workforce, in February this year as a result of marketing cutbacks by Dell.