| Official Name: | Rio Maior |
| Type: | municipality |
| Flag Border: | no |
| Coordinates: | 39.3333°N -64°W |
| Region: | Oeste e Vale do Tejo |
| Cim: | Lezíria do Tejo |
| District: | Santarém |
| Parishes: | 10 |
| Leader Party: | PSD |
| Leader Name: | Luís Filipe Santana Dias |
| Area Total Km2: | 272.76 |
| Population Total: | 21,192 |
| Population As Of: | 2011 |
| Holiday: | November 6 |
Rio Maior (pronounced as /pt-PT/) is a municipality in the Santarém District in Portugal. The population in 2011 was 21,192,[1] in an area of 272.76 km².[2]
The present mayor is Isaura Morais of the Social Democratic Party (PSD), the first woman to be elected mayor in the municipality. The municipal holiday is November 6.
Administratively, the municipality is divided into ten civil parishes (freguesias):[3]
Rio Maior has a Mediterranean climate with warm to hot, dry summers and mild, wet winters. Rio Maior registered a temperature of on 4 August 2018[4] and on January and February.