Year 1018 (MXVIII) was a common year starting on Wednesday (liNk will display the full calendar) of the Julian calendar.
- January 30 – The Peace of Bautzen is signed between Poland and Germany.
- July 22–23 – Bolesław I Chrobry, Duke of Poland, defeats Yaroslav the Wise in the Battle of the River Bug. Yaroslav retreats to Novogrod, abandoning Kiev.
- July 29 – Dirk III, Count of Holland, defeats an army sent by Henry II, Holy Roman Emperor, in the Battle of Vlaardingen.
- August – Leader of the remaining Bulgarian resistance, Ivats, is blinded and captured by strategos Eustathios Daphnomeles, confirming Bulgaria's position as part of the Byzantine Empire.
- August 14 – Bolesław accepts the surrender of Kiev by the Pechenegs. He reinstates Sviatopolk as Grand Prince of Kiev.
- c. October? – In Southern Italy, at the second battle of Cannae, the Lombard adventurer Melus of Bari and his Norman mercenaries are defeated by the Byzantine army led by the Catepan Basil Boioannes.
- Probable date