|Millennium:||1st millennium BC|
|89 BC by topic|
|Gregorian calendar||89 BC|
|Ab urbe condita||665|
|Ancient Egypt era||XXXIII dynasty, 235|
|- Pharaoh||Ptolemy X Alexander, 19|
|Ancient Greek era||172nd Olympiad, year 4|
|Balinese saka calendar||N/A|
|Chinese calendar||辛卯年 (Metal Rabbit)|
2608 or 2548
— to —
壬辰年 (Water Dragon)
2609 or 2549
|Coptic calendar||−372 – −371|
|Ethiopian calendar||−96 – −95|
|- Vikram Samvat||−32 – −31|
|- Shaka Samvat||N/A|
|- Kali Yuga||3012–3013|
|Iranian calendar||710 BP – 709 BP|
|Islamic calendar||732 BH – 731 BH|
|Minguo calendar||2000 before ROC|
|Seleucid era||223/224 AG|
|Thai solar calendar||454–455|
38 or −343 or −1115
— to —
39 or −342 or −1114
Year 89 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Strabo and Cato (or, less frequently, year 665 Ab urbe condita). The denomination 89 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- Consuls: Gnaeus Pompeius Strabo and Lucius Porcius Cato.
- Social War:
- Lex Plautia Papiria extends citizenship to all Italians who applied for it within 60 days. The new citizens are enrolled in eight designated tribes, to prevent domination of the assemblies.
- Lex Pompeia grants Latin rights to cities in Cisalpine Gaul.
- Pompeii is annexed by the Roman Republic.
- Cicero ends his service in the Roman army.
- Aulus Sempronius Asellio, Roman praetor (murdered by creditors)
- Titus Didius, killed in battle during the Social War
- Marcus Aemilius Scaurus, Roman politician (b. c. 163 BC)
- Lucius Porcius Cato, Roman politician and general