Khmelnytskyi (Ukrainian: Хмельницький, IPA: [xmelʲˈnɪtsʲkɪj] ^ⓘ) is a city in western Ukraine. Located on the Southern Bug, it serves as the administrative centre of Khmelnytskyi Oblast as well as Khmelnytskyi Raion within the oblast. With a population of 274,452 (2022 estimate), Khmelnytskyi is the second-largest city in the historical region of Podolia, after Vinnytsia.

The city was first mentioned in 1431 as a Polish military post, where it was known as Płoskirów under Polish rule. It was seized by Cossacks during the Khmelnytsky Uprising and later ruled by the Ottomans until 1699. It was passed to Russia in 1793, as a result of the Second Partition of Poland, and became part of the newly-formed Podolia Governorate, where it became known as Proskuriv or Proskurov. From 1917 to 1920, it was controlled by the short-lived Ukrainian People's Republic before becoming part of Soviet Ukraine. The city's Jewish population fell from 42 per cent in 1939 to 10 per cent in 1959 as a result of the Holocaust in Ukraine. In 1954, it was renamed Khmelnytskyi in honor of the Cossack leader Bohdan Khmelnytsky.

Khmelnytskyi is the location of a rail junction and an important industrial centre, as well as a centre for higher education such as the Khmelnytskyi National University and the Khmelnytskyi Oblast Ukrainian Music and Drama Theater.

Khmelnytskyi had several names throughout history. In the oldest written evidence about this settlement, the name of the city was mentioned as Ploskirowce, while later documents mentioned its name as Płoskirów, which probably comes from the name of the Ploska River.

In 1793, the city was renamed Proskurov, which appeared on the decree to create Podolia Governorate. This toponym is very similar to the name "proskura", which is a bread in the liturgical service.

On 16 January 1954, Proskuriv was renamed to Khmelnytskyi in honor of Bohdan Khmelnytsky, the Cossack hetman who rebelled against the Polish–Lithuanian Commonwealth.

The city foundation date is uncertain. The territory where Khmelnytskyi is situated has been inhabited for a very long time. Many archaeological discoveries have been made in the city suburbs. For example, to the East of Lezneve district, there was a settlement from the Bronze Age 2000 B.C., and from Scythian times from 7–3 century B.C. The first mention of the city was written with Cyrillic alphabet. The earliest known mention in historical sources was in 1431, when it was known as Płoskirów (Ploskirov, Плоскиров) and was part of the Kingdom of Poland. It was a royal city.

Polish rule was briefly interrupted by the Ottomans between 1672 and 1699. During this period, it was a subdivision of Mejibuji sanjak in Podolia Eyalet as Poloskiruf. After the Second Partition of Poland in 1793, the city was annexed by the Russian Empire and was renamed Proskurov (Проскурoв). According to the Russian census of 1897, Proskurov with a population of 22,855 was the fifth largest city of Podolia after Kamianets-Podilskyi, Uman, Vinnytsia and Balta. In 1920 it became part of Soviet Ukraine. In 1954 the city was finally renamed Khmelnytskyi (Хмельницький) in the honor of the 300th anniversary of a treaty negotiated by Bohdan Khmelnytsky.