Iliescu was a leader of the revolution that overthrew Nicolae Ceauşescu in December 1989. He was elected president on May 20, 1990, and after the adoption of the 1991 constitution, he won another 4-year term in 1992. He was defeated in the 1996 election by Emil Constantinescu, but won the 2000 election and began his current term on December 20 of that year.

Iliescu was a member of Romanian Communist Party (PCR) and held state office before the overthrow of Ceauşescu. He was a founding member of the National Salvation Front(FSN: Frontul Salvării Naţionale), and followed it in its vagaries: FDSN (Frontul Democrat al Salvării Naţionale), then the Social Democratic Party of Romania (PDSR).

His political convictions have changed with the times, from a staunch proponent of socialism to that of a social democrat. In 2003, he promoted a new constitution designed to facilitate the goal of Romanian entry into the European Union, and it was approved in a referendum by 90% of the vote.