Commissioner O’Sullivan joined An Garda Síochána in 1981 and has more than 30 years of professional policing experience across a wide range of both operational and administrative function areas and has worked in a broad range of police disciplines at both national and international level.
2000: Promoted to Superintendent and served in the Garda College with responsibility for specialist training and as a Detective Superintendent in the Garda National Drugs Unit.
2003: Promoted to Chief Superintendent and served as Detective Chief Superintendent at the Garda Technical Bureau and also in Human Resource Management.
2007: Promoted to Assistant Commissioner and served in the Western Region followed by Human Resource Management and was appointed Assistant Commissioner, Crime and Security in June 2009.
2011: Promoted to Deputy Commissioner Operations.
2014: Appointed as Commissioner on the 25th November 2014