He served as a Fine Gael Teachta Dála (TD) for twenty-five years and as a Minister of State from 1982 to 1987.
[1] He played Gaelic football for his local club Dunmore McHales and at senior level for the Galway county team in the 1960s.
His father, Michael Donnellan, had won an All-Ireland Senior Football Championship (SFC) medal with Galway in 1925, later becoming a TD for Clann na Talmhan.
He completed a great run of success by capturing back-to-back county championship and Connacht club titles in 1968 and 1969.
Three years later in 1963 he captured a second provincial title; however on that occasion Dublin defeated the men from the west in the All-Ireland SFC final.
The following year he won a fifth Connacht Championship title before qualifying for a fourth consecutive All-Ireland final appearance.
Donnellan's father Michael died suddenly in September 1964, and at the resulting by-election in December John was elected to Dáil Éireann as a Fine Gael TD for the Galway East constituency.