Hemingway, together with content and media strategists Simon Mustoe and Ben Bose, will lead the 14-strong editorial team, which is using tools such as social media, interactive video and podcasts to enhance clients' online presence.
Prior to her appointment at iCrossing, Hemingway led the online editorial team in the Home Office Communications Unit, where she ran an internal online news service and TV channel.
In her new role, she reports to Antony Mayfield, iCrossing vice-president head of social media. Mayfield said Hemingway will help to extend iCrossing's approach to connecting brands online.
Regional journalists Hannah Wood and Jo-Ann Hodgson also joined iCrossing's content division this month. Recent work by iCrossing's editorial department includes a new sub-domain page for insurance company MoreTh>n.
In January, iCrossing integrated its UK social media agency Spannerworks into the iCrossing brand after acquiring it for more than £10m in February 2007.
The company's UK division is in the process of moving into larger London premises near Victoria.