In the UK, Timpson[0] are a well known example of a national employer not only willing to hire ex-offenders but one that does so proudly, and indeed offer training to prisoners before they are even released. They have tried to convince other companies to follow their lead but with limited success. That said, we also have Clean Sheet[1] through which employers can expressly publicise their willingness to employ ex-offenders.
I find it extremely admirable. Best of luck with your approach.
[0] See for example this archived blog post: https://web.archive.org/web/20150222003545/http://www.timpso... or a search for "Timpson ex-offenders" https://www.google.co.uk/search?q=timpson+ex-offenders
[1] http://cleansheet.org.uk/