[1] Joseph Deiss started his political career in 1981 as a representative of his party in the Grand Council of Fribourg.

In 1996 he was made president of the committee in charge of the total revision of the Swiss Federal Constitution.

Deiss was elected to the Swiss Federal Council on 11 March 1999, along with his erstwhile colleague Ruth Metzler.

Together with Adalbert Durrer and Remigio Ratti, he was one of three official candidates proposed by the CVP/PDC for the seat of retiring Federal Councillor Flavio Cotti.

In 2009 Joseph Deiss was awarded an honorary degree Doctor Honoris Causa from Business School Lausanne in recognition of his achievements to reinforce and expand the political and economic position of Switzerland.