There seems to be no record of the building of the castle.
In 1288-89 it is noted that the rent paid for Dunsoghly by Geoffrey Brun was 74s. and fivepence. Nearly two hundred years later (1422) the King granted to Henry Stanyhurst the custody of all the messuages which had belonged to John Finglas to hold rent free during the minority of the heir. Two years later Roger Finglas is forgiven his arrears of Crown rent out of the lands and tenants of Dunsoghly and Oughtermay.
Soon after this the land seems to have passed to Sir Roland Plunkett, the younger son of Sir Christopher Plunkett, Baron of Killem, and Lord Deputy of Ireland, 1432, this family being a branch of the Fingall family.
In 1446 Sir Rowland Plunkett, of Dunsoghly Castle, was appointed Chief Justice of the King’s Bench, and later his son, Sir Thomas Plunkett, became Chief Justice of Common Pleas.
The Crown leased, in 1547, to John Plunkett, of Dunsoghly, gent., all the tithes in Dunsoghly and Oughtermay, in the Parish of St. Margaret of Dowanor, part of the possessions of the Chancellor of the late Cathedral of St. Patrick, at a rent of five marks. He was also to provide a chaplain for the church of Dowanor.
This John Plunkett was grandson to Sir Thomas, and also received knighthood. He was made Chief Justice of the Queen’s Bench in 1559. He died twenty-three years later, seized of the manors of Dunsoghly and Oughtermay.
Sir John built the private chapel belonging to the castle, and also the chantry of St. Margaret’s.
In 1590 Christopher Plunkett, of Dunsoghly, is included in the list of the English Pale; and twenty years later he surrendered Dunsoghly to the King, who re-granted it to him with additional lands on account of his own and his family’s service to the Crown.
Colonel Richard Plunkett, of Dunsoghly, was an active supporter of the Lords of the Pale in 1641, and a reward of £400 was offered for his head by the Lords Justices and Council.
In 1657 the Down Survey says that the “chiefest places in the Barony of Coolock are Malahide and Dunsoghly.” “There is in Dunsoghly a good castle, and a house adjoining it (James Plunkett).”