乌波卢岛（Upolu Island），是萨摩亚独立国两主岛中面积较小的一个，也是人口较多、经济较发达的一个，首都阿皮亚即位于该岛北部。该岛西隔阿波利马海峡与萨瓦伊岛相望。

乌波卢岛是一个位于西南太平洋的火山岛，面积1125平方公里，人口约11万。英国作家罗伯·路易斯·史蒂文生曾在岛上买下一座种植园长期居住，1894年在此逝世并埋葬于岛上。

在波利尼西亚神话（特别是萨摩亚）中，乌波卢是在同名岛上的第一个女人。18世纪末19世纪初，该岛有时被叫做Ojalava或Ojolava.

一种极小的蜘蛛生活在乌波卢岛上。据2005版吉尼斯世界记录记载，该蜘蛛大小相当于该书的一个句点。

Upolu is an island in Samoa, formed by a massive basaltic shield volcano which rises from the seafloor of the western Pacific Ocean. The island is 75 kilometres (47 miles) long, 1,125 square kilometres (434 square miles) in area, and is the second largest in geographic area as well as with 135,000 people the most populated of the Samoan Islands. Upolu is situated to the southeast of the "big island", Savai'i. The capital Apia is in the middle of the north coast with Faleolo International Airport at the western end of the island. The island has not had any historically recorded eruptions, although three lava flows date back only a few hundred to a few thousand years.