Halling's brief will be to help grow assignments from existing clients, in addition to co-ordinating the WPP-owned operation's new-business initiatives.
Her appointment comes four months after Red Cell signed Red Spider's Charlie Robertson as its chief strategic officer.
Amanda Walsh, Red Cell Europe's chief executive, said: "Katie's arrival is a sign we are getting the network into shape. Previously, we were a group of very individual agencies and there was nobody to pull our efforts together.
Katie has high-level management experience."
Halling's career includes two stints at Bartle Bogle Hegarty (where she was the head of account management), Abbott Mead Vickers BBDO and Wieden & Kennedy in Amsterdam, where she was a management supervisor.
She joined TBWA\London in November 2002 to run one of its four client groups. However, a year ago, she decided to take time out of the business to live in France.