Mr Milligan-Croft has more than 25 years' experience in the advertising and creative sectors, working on multi-national accounts for companies such as TBWA, O&M and McCann's in Ireland.
He has won more than 100 awards for his work for brands including Heinz, Peugeot, Coors and Cadbury's.
Most recently he has worked on many social marketing camapigns, an area in which ICE also specialises.
He said: "Joining ICE is a fantastic opportunity for me to follow my passion for crafting communications which make a genuine and sustained difference within our communities.
"I'm incredibly passionate about harnessing my experience in commercial advertising and brand development to help support behaviour change on a range of social issues and am looking forward to driving forward innovative and insightful campaigns for a wide range of clients."
ICE is based in Birkenhead and employs 50 people throughout the UK. It has offices in London, the South West and the North East.
ICE chief executive Stuart Jackson said: "Attracting a talented creative director of David's calibre is testament to the innovative work we're doing to help clients to connect with target audiences and develop their brand positions in increasingly tough regional and national marketplaces.
"Not only does he bring creative innovation and commercial insight, but he also has the proven leadership skills to bring out the best in our talented team of copywriters, designers and multi-media specialists."