He is the managing director of Keith Hay Homes Limited, founded by his father.

He was subsequently elected to the Auckland City Council on the Citizens & Ratepayers ticket, and served as deputy mayor between 1991 and 1998 under Les Mills, and from 2001 to 2004 and 2007 to 2010 under John Banks.

His achievements on council included the restoration of the Civic Theatre and the establishment of Metrowater, and he supported the formation of the Auckland supercity.

[4] In the early 1990s, Hay opposed the gay pride 'Hero parade' on the grounds of taste and public decency, stating: "If it was the Girl Guides behaving like that, I'd object.

[9] In the 2011 New Year Honours, Hay was appointed a Companion of the New Zealand Order of Merit for services to local-body affairs and the community.