He is also currently a member of the Government Review Body on Higher Remuneration in the Public Sector and a Director of the National Pensions Reserve Fund Commission (Ireland).
Until his appointment to the Central Bank and Financial Services Authority of Ireland, Hillery was chairman of UniCredito Italiano Bank (Ireland) Plc.
He was an Executive Director, representing Ireland and Denmark, of the European Bank for Reconstruction and Development (EBRD) London (1994–97).
Hillery was a director of the Central Bank and Financial Services Authority of Ireland from 1 May 2008, succeeding Martin O'Donoghue, until he stepped down in October 2010.
Hillery is a former member of Dáil Éireann and Seanad Éireann (1977–1994). In 1977 he was elected to the 14th Seanad for Fianna Fáil by the Administrative Panel, and after unsuccessfully contesting the 1981 general election in Dún Laoghaire he was returned to the 15th Seanad, from 1981–1982. He did not sit in the brief 16th Seanad, but was re-elected to the 17th Seanad in 1983, where he served until he was elected as Teachta Dála (TD) for Dún Laoghaire at the 1987 general election.
At the 1992 general election he lost his Dáil seat to Helen Keogh of the Progressive Democrats, and was nominated by the Taoiseach to the 20th Seanad. He resigned as Senator on 5 May 1994, to take up his post with the European Bank for Reconstruction and Development.