She joins next week to oversee its Carmen Media account, among others, reporting to UK chief executive Vikki Stace.
The move reunites Curtis with former WS international deputy CEO Michael Murphy, now Trimedia international CEO. Curtis left WS three years ago to become an independent consultant.
Trimedia has opted not to replace former public affairs MD Simon Elliott who defected to Burson-Marsteller (PRWeek, 7 January).
'We have refocused the company on the corporate sector since Simon's departure,' said Stace.