| Uelsby Ølsby | |
| Image Coa: | DEU Uelsby COA.svg |
| Coordinates: | 54.6°N 43°W |
| Image Plan: | Uelsby in SL.PNG |
| State: | Schleswig-Holstein |
| District: | Schleswig-Flensburg |
| Amt: | Südangeln |
| Elevation: | 34 |
| Area: | 10.6 |
| Postal Code: | 24860 |
| Area Code: | 04623 |
| Licence: | SL |
| Gemeindeschlüssel: | 01 0 59 093 |
| Website: | www.amt- suedangeln.de |
| Mayor: | Ulrich Bachler |
Uelsby (Danish: Ølsby) is a municipality in the district of Schleswig-Flensburg, in Schleswig-Holstein, Germany.