The twenty-first election to Cardiganshire County Council took place in April 1958. It was preceded by the 1955 election and followed by the 1961 election.
41 candidates were returned unopposed resulting in only nine contests.
Eight aldermen retired, of whom four sought election. Retiring councillors stood down in favour of aldermen in Aberystwyth, Llanllwchaiarn and at Bow Street, where D.R. Morgan, first elected in 1922, was again returned. At Aberporth, however, retiring alderman the Rev. Evan Melinfab Lewis was opposed by the retiring councillor, the Rev. Tegryn Davies.
With only nine contests, attention focused entirely on the contest at Aberporth between the retiring alderman and councillor, both of whom were nonconformist ministers. Evan Melinfab Lewis, Baptist minister at Penparc, was a previous chairman of the council and a member since 1937, while Tegryn Davies was the Congregational minister at Aberporth. Denominationlism featured prominently in the contest and on a turnout of 88%, Davies was returned. It was reported that the crowd that gathered at Aberporth to hear the result was among the largest ever seen at a Cardiganshire local authority election. Two other sitting members were also defeated.
In addition to the 50 councillors the council consisted of 16 county aldermen. Aldermen were elected by the council, and served a six-year term. Following the 1955 election, there were eight aldermanic vacancies which were filled at the annual meeting.
The following retiring aldermen was re-elected:
In addition, the following new aldermen were elected:
Evan Evans, Cilcennin, stood down after over thirty years as a member of the council
Eight by-elections were called following the election of aldermen. Four of the wards were contested. At Bow Street, the retiring councillor who had stood down in favour of long-serviong alderman D.R. Morgan was returned unopposed.