Born in Boțești, Argeș County, Diaconescu began his political career in 1936, when he joined the Peasants' Party (PNȚ) youth wing.

Diaconescu co-founded the Christian Democratic National Peasants' Party (PNȚCD) in 1989, just after the revolution.

[1] Diaconescu served as the Speaker of the Chamber of Deputies, the lower house of the Romanian Parliament, from 1996 to 2000.

"[1] Former Romanian Prime Minister Victor Ciorbea paid tribute to Diaconescu saying, "Ion Diaconescu understood that faith and principles are national treasures, and he didn’t betray these (values), enduring 17 years in communist prisons.

"[1] One of Romania's best known political activists, Doina Cornea, also praised Diaconescu's life and career, "Today’s politicians only think about their own interests.