The post was created in May 1560 by the Lord Deputy of Ireland, Thomas Radclyffe, 3rd Earl of Sussex.

The role was modelled in part on the role of Secretary of State in England, and was intended to be distinct from the clerks of the Irish Privy Council or the Governor's Private Secretary.

[1] Whilst the nature of the role evolved other time, originally the holder was expected to:[2] Other, less common functions included:[2] In part due to the absence of the Southwells during their time in the role, it became largely ceremonial, with more correspondence being managed directly by the Lord Lieutenant and his Chief Secretary, or alternatively the Lords Justices (who themselves became defunct after 1765).

Richard Cooke, for instance, acted as both Chancellor of the Exchequer of Ireland and Secretary of State at the same time.

No Secretary of State was appointed after the 1800 Acts of Union; in 1802 the last appointee resigned to become Speaker of the UK House of Commons.