|Centuries:||4th century – 5th century – 6th century|
|Decades:||390s 400s 410s – 420s – 430s 440s 450s|
|Years:||424 425 426 – 427 – 428 429 430|
|427 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1180|
|Chinese calendar||丙寅年 (Fire Tiger)
3123 or 3063
— to —
丁卯年 (Fire Rabbit)
3124 or 3064
|- Vikram Samvat||483–484|
|- Shaka Samvat||349–350|
|- Kali Yuga||3528–3529|
|Iranian calendar||195 BP – 194 BP|
|Islamic calendar||201 BH – 200 BH|
|Minguo calendar||1485 before ROC
|Seleucid era||738/739 AG|
|Thai solar calendar||969–970|
Year 427 (CDXXVII) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Hierus and Ardabur (or, less frequently, year 1180 Ab urbe condita). The denomination 427 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.
- Flavius Aetius, Roman general (magister militum), arrives in southern Gaul with an army (40,000 men) and defeats the Visigoths under king Theodoric I who besiege the strategic city of Arles.
- Bonifacius, Roman governor (Last of the Romans), revolts in Africa against emperor Valentinian III. Under the influence of Aetius, he is convicted of treason by empress-mother Galla Placidia.
- The Ephthalites (White Huns) invade Western Asia and reduce the Sasanian Empire threat to the Eastern Roman Empire. King Bahram V sends an expeditionary force into Khorasan.
- King Jangsu transfers the Goguryeo capital from Gungnae City (modern Ji'an, Jilin) on the banks of the Yalu River to Pyongyang (modern Korea).
- Erbin of Dumnonia, Brythonic king (approximate date)
- Qi Gaodi, Chinese emperor of the Southern Qi Dynasty (d. 482)
- Wang Xianyuan, empress and wife of Song Xiaowudi (d. 464)
- Guisin, king of Baekje (Korea)
- December 24 – Sisinnius I, archbishop of Constantinople
- Tao Qian, Chinese poet of the Eastern Jin Dynasty (b. 365)