Travis, the current part-time director, is leaving to take the top comms role at the children's charity in the Philippines.
She leaves on 10 April but the charity is hoping to have someone in position by mid-May.
Victoria Rae, who job-shares the comms director post with Travis, will continue in her role.
Meanwhile the charity is also looking to fill a new position in its public affairs team, heading its Born Free from HIV campaign. Current campaigns co-ordinator Sarah Hoole is relocating to Ireland.
Last month, UNICEF launched a digital HIV awareness campaign that featured Gwyneth Paltrow and Sir Roger Moore.