| Country: | England |
| Static Image: | Thatched cottage at Preston Crowmarsh, Oxfordshire.jpg |
| Static Image Caption: | Cottages in Preston Crowmarsh |
| Coordinates: | 51.613°N -1.111°W |
| Official Name: | Preston Crowmarsh |
| Civil Parish: | Benson |
| Shire District: | South Oxfordshire |
| Shire County: | Oxfordshire |
| Region: | South East England |
| Constituency Westminster: | Henley |
| Post Town: | Wallingford |
| Postcode District: | OX10 |
| Postcode Area: | OX |
| Dial Code: | 01491 |
| Os Grid Reference: | SU616908 |
| Website: | Benson Parish Council |
Preston Crowmarsh is a hamlet in Benson civil parish in South Oxfordshire. It is on the River Thames 1miles north of Wallingford. The river can be crossed on foot here at Benson Lock.