He was the only son of William Piers, a Yorkshireman who had been granted land in Ireland by Elizabeth I in return for military and other services. His mother was Ann Holt, of Holt Castle on the north Welsh borders. Henry married Jane Jones, daughter of Thomas Jones, Archbishop of Dublin, and had eight children. He served as the secretary to Lord Deputy Chichester and represented the potwalloper constituency of Baltimore in the 1613 Irish Parliament. In addition to his father's estates at Tristernagh he also acquired plantation land in Cavan.
Henry Piers converted to Catholicism later in life, after "conversing with many of the Romish church" according to a family memoir (which also claimed he did so "against the advice of his wife"). He subsequently travelled on the Continent for some 8 years and on his return converted a number of his children, one of whom, Thomas Piers, was said to have became a Franciscan friar. He also wrote a book describing his travels, the manuscript of which eventually came to Sir James Ware.
Piers was succeeded in his estates by his eldest son, who was later knighted, becoming Sir William Piers. Henry's grandson Sir Henry Piers, a soldier and notable antiquarian, was created a baronet in 1661, founding the Piers baronets of Tristernagh. One of his descendants was Sir John Piers, who was involved in a notorious adultery case.
Henry Piers is buried in a tomb in the now-ruined chapel of Templecross, which stands at the gates to Tristernagh demesne. An altar monument bearing the Piers arms and a Latin inscription still exists in the ruins; the inscription commemorates Henry Piers as a "hospitable native" of "renowned piety" who repaired Tristernagh Abbey. A translation and drawing of the inscription are given in James Woods' Annals of Westmeath.
- The Peerage of Ireland, v2, 1789, p.201
- Clarke, A. Prelude to Restoration in Ireland, CUP, 1999, p.191
- Mícheál Ó Cléirigh, Annals of the Kingdom of Ireland, v5, 1856, p.1620
- Brewer, J. N. The Beauties of Ireland, v2, 1826, p.239
- Woods, J. Annals of Westmeath, Sealy, Bryers and Walker, 1907, p.307