It covered the area of four former districts from the administrative county of Flintshire, which were all abolished at the same time:[1] The name "Delyn" was formed by combining the names of the area's principal rivers: the Dee and the Alyn.

"Y Delyn" is also Welsh for "The Harp", a fact reflected in the borough's coat of arms.

In 1996 the borough was abolished under the Local Government (Wales) Act 1994, which saw Clwyd County Council and its constituent districts abolished, being replaced by principal areas, whose councils perform the functions which had previously been divided between the county and district councils.

Delyn House and Flint Guildhall (also known as Flint House) thereafter served as the council's main offices, with the Civic Offices in Holywell retaining some departments.

After the council's abolition, the Civic Offices in Holywell were demolished in August 2002 to make way for a Lidl supermarket, which later opened in the summer of 2007 as a replacement of the nearby Kwik Save,[8] and Flint Guildhall was demolished around the same time to make way for a block of flats.