Grondin served as Mayor of Shawinigan-Sud from 1977 to 1985. He did not run for re-election in 1985 and was succeeded by Claude Pinard.
Member of Parliament
On 29 September 1986, Grondin won a by-election and filled the seat left by Jean Chrétien, becoming the Liberal Member for the district of Saint-Maurice. Chrétien had left federal politics in February that year and would stay out of office until he became Liberal party leader and subsequently Prime Minister.