| Marlieux | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Marlieux 01.svg |
| Arrondissement: | Bourg-en-Bresse |
| Canton: | Châtillon-sur-Chalaronne |
| Insee: | 01235 |
| Postal Code: | 01240 |
| Mayor: | Jean-Paul Grandjean[1] |
| Term: | 2020 - 2026 |
| Coordinates: | 46.065°N 5.07°W |
| Elevation M: | 230 |
| Elevation Min M: | 263 |
| Elevation Max M: | 282 |
| Area Km2: | 16.85 |
Marlieux (in French pronounced as /maʁljø/; Marelyô) is a commune in the Ain department in eastern France. Marlieux—Châtillon station has rail connections to Bourg-en-Bresse and Lyon.
The river Chalaronne forms part of the commune's western border.
Marlieux has an oceanic climate (Köppen climate classification Cfb). The average annual temperature in Marlieux is . The average annual rainfall is with October as the wettest month. The temperatures are highest on average in July, at around, and lowest in January, at around . The highest temperature ever recorded in Marlieux was on 13 August 2003; the coldest temperature ever recorded was on 6 January 1971.