Born in Llanelli, Evans was educated at Llanelli Grammar School and Swansea University College. He served on the West Bromwich education committee and acted as the Labour agent for the general elections in 1955 and 1959 in the Birmingham Small Heath constituency. He was secretary of Birmingham and District Co-operative Party.
Evans was first elected to Parliament in the 1964 general election for the constituency of Birmingham Yardley. From 2 May 1966 to 26 September 1966, Evans was a substitute member of the Parliamentary Assembly of the Council of Europe. From 1968 to 1970 he was Comptroller of the Household in the Wilson Government. Evans lost his seat in the 1970 general election to Conservative Derek Coombs.
Evans re-entered Parliament in the February 1974 general election for the Welsh seat of Aberdare. This seat was abolished in 1983, and Evans was elected for the new Cynon Valley constituency. He died the following year, aged 56, in Hillingdon, and a by-election was held to replace him.
- "Mr Ioan Evans". assembly.coe.int. Retrieved 2008-07-10.
- Hansard 1803–2005: contributions in Parliament by Ioan Evans
|Parliament of the United Kingdom|
|Member of Parliament for Birmingham Yardley
1964 – 1970
|Member of Parliament for Aberdare
Feb 1974 – 1983
|New constituency||Member of Parliament for Cynon Valley
1983 – 1984
|Comptroller of the Household
1968 – 1970