Kieran was a continuity announcer on RTÉ One during 1987 and 1988.
He is a former producer, reporter, and researcher with RTÉ, having worked on popular television and radio programmes, including The Late Late Show, Prime Time, and Liveline.
He was named News and Current Affairs Journalist of the Year in 1999, and is a former chair of the Dublin Broadcasting Branch of the National Union of Journalists.
He had served as head of communications and research for the Garda Síochána Ombudsman Commission from 2007. In December 2011, he was appointed to the Garda Síochána Ombudsman Commission.
He has a doctorate in governance from the School of Law at Queen’s University Belfast, and is a member of the executive committee of the British and Irish Ombudsman Association.