Yambol (Bulgarian: Ямбол) is a city in southeastern Bulgaria, an administrative centre of Yambol Province. It lies on both banks of the Tundzha river in the historical region of Thrace. As of February 2011, the town has a population of 72,843 inhabitants. It is occasionally spelt 'Jambol'.

The administrative centres of two municipalities are situated in Yambol. One is of the rural area of Tundzha Municipality and the other is of the homonymous Yambol Municipality that embraces the city itself.

Yambol Peak on Livingston Island in the South Shetland Islands, Antarctica is named after Yambol^{[citation needed]}.

The surrounding area has been inhabited since the Neolithic and was the location of the ancient Thracian royal city of Kabyle. It was founded or refounded by Philip II of Macedon as an Ancient Greek polis. Conquered by the Romans, but destroyed by the Avars in 583). Yambol was founded by Roman Emperor Diocletian in AD 293; though it was named Diospolis (Διόςπόλις in Greek 'city of Zeus'), the name also reflected the emperor's name. The name later evolved through Diampolis (Διάμπόλις), Hiambouli (Ηιάμβόυλι; in Byzantine chronicles), Dinibouli (دنبلي; Arabic chronicles), Dbilin (Дбилин; in Bulgarian inscriptions), and Diamboli (Диамбоюли) to become Yambol. As the Slavs and Bulgars arrived in the Balkans in the Middle Ages, the fortress was contested by the Bulgarian Empire and the Eastern Roman Empire, becoming part of Bulgaria in 705 AD during the reign of Khan Tervel. It has been an important Bulgarian center ever since.