Davies will take the title of managing director and will also run the Best Buy Mobile account, the joint venture launched by the US retailer Best Buy and the Carphone Warehouse.
CHI New York is currently working on the November launch of ten Best Buy Mobile stores. A national launch of the brand is expected to follow. The agency has produced a series of print ads featuring New Yorkers on the streets of Manhattan.
The CHI founding partner Johnny Hornby said: "We've been trying to lure Victoria to work with us for a long time and we're delighted she's now with us."
Davies resigned from TBWA\London in June without a job to go to. Her departure coincided with the resignation of Suzie Shaw as the client services director.
Davies joined the agency in 2004 and was promoted to managing director in June 2006, replacing Matt Shepherd-Smith, who was promoted to chief executive.
Previously, she was the joint managing director alongside Neil Hourston, who left TBWA\ to take up the position of executive planning director at Grey London earlier this month.
TBWA\London promoted its head of planning, Tom Morton, to fill Hourston's position. It has yet to appoint a new managing director.