Ionescu (Francisized as Ionesco or Jonesco) is a Romanian surname, derived from the male given name Ion. It may refer to:
- Adrian Silvan Ionescu, historian and art critic
- Alexandre Sadi-Ionesco, librarian and bibliographer
- Alexandru Ionescu, bobsledder
- Alexandru Ionescu, socialist militant
- Anton Ionescu, politician
- Carmen Ionescu, discus thrower
- Cazimir Ionescu, politician
- Claudiu Eugen Ionescu, handball player
- Constantin Al. Ionescu-Caion, journalist
- Constantin Dudu Ionescu, politician
- Constantin Ionescu Gulian, philosopher and journalist
- Cristian Ionescu, politician
- Elisabeta Ionescu, handball player
- Emanoil Ionescu, soldier
- Eugène Ionesco, playwright
- Eva Ionesco, actress
- Gelu Ionescu, literary historian and critic
- George Ionescu-Gion, journalist and historian
- Gheorghe Ionescu, painter
- Gheorghe Ionescu-Siseşti, agronomist
- Ghiţă Ionescu, political scientist
- Grigore Ionescu, architect and historian
- Ilarion Ionescu-Galaţi, violinist and conductor
- Ioan Ionescu-Dolj, jurist
- Ion Ionescu de la Brad, agronomist and economist
- Irina Ionesco, photographer
- Jojo (Cătălina Alexandra Ionescu), pop singer
- Marian Ionescu, pioneer cardiac surgeon
- Marian Ionescu, pop drummer
- Mircea Ionescu Quintus, politician
- Nae Ionescu, philosopher
- Nicolae Ionescu, politician
- Nicolae Ionescu-Pallas, physicist
- Nicolae Ionescu-Siseşti, neurologist
- Radu Ionescu, literary critic and poet
- Raicu Ionescu-Rion, socialist journalist, sociologist and art critic
- Şerban Ionescu, actor
- Silvan Ionescu, visual artist
- Silviu Ionescu, former Chargé d'Affaires of the Romanian Embassy in Singapore
- Ştefan Ionescu Valbudea, sculptor
- Take Ionescu, politician
- Theodor V. Ionescu, physicist
- Thoma Ionescu, surgeon
- Tudor Ionescu, socialist politician
- Valentin Ionescu, politician
- Vali Ionescu, long jumper
- Vasile Constantin Niculae Ionescu-Galbeni, politician
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