Hawker was previously director of children’s services at Brighton and Hove City Council.
He is to take up the post of director general for children, education, lifelong learning and skills at the Welsh Assembly Government later this summer.
Hawker said he would be stepping down from his responsibilities at the Association of Directors of Children’s Services, where he is currently chair of the standards, performance and inspection policy committee and the research committee.
He said: “The integration of children’s services following Every Child Matters has been one of the most positive and constructive changes in social policy in our generation. Wales has arrived at a different model but the principles are the same and I am looking forward to working through some of these principles.”
Michael O’Connor will take over the role of acting director of children’s services at Westminster until a permanent replacement for Hawker is appointed.