Walsh was born in May 1943 in Ballineen, County Cork, the third child of five sons and three daughters of Richard Walsh, a farmer of Kilmoylerane, Ballinascarthy, County Cork, and his wife Margaret (née Dullea).[2] He was educated at St Finbarr's College, Cork, and University College Cork, where he qualified with a degree in Dairy Science in 1970. During his time at the university, he became involved in politics, establishing the first Fianna Fáil cumann in the university. Walsh began his career as a researcher in the National Dairy Research Centre at Moorepark, near Fermoy, before becoming managing director of Strand Dairies in Clonakilty, County Cork.[2]
When Ireland was confronted with a foot-and-mouth disease crisis in 2001, Walsh introduced control measures to prevent a full-scale outbreak, such as curtailing the movement of animals during football games and postponing sports events, including the 2001 Six Nations Championship.[5]
He received several awards, including the Légion d'honneur[6] and the Grand Cross of the Agricultural Order of Merit of Spain.[7] On 13 August 2004, he announced that he would retire from the Cabinet after spending 14 years of his career at the Department of Agriculture.[8]