| Serio | |
| Map: | Serio.png |
| Source1 Location: | Monte Torena, Italy |
| Mouth: | Adda |
| Mouth Location: | Bocca di Serio, south of Crema |
| Mouth Coordinates: | 45.2581°N 9.6936°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Italy |
| Length: | 124km (77miles) |
| Source1 Elevation: | 2583m (8,474feet) |
| Tributaries Left: | Bondione, Ogna, Romna |
| Tributaries Right: | Acqualina, Morla |
The Serio (Lombard: Sère) is an Italian river that flows entirely within Lombardy, crossing the provinces of Bergamo and Cremona. It is 124km (77miles) long and flows into the Adda at Bocca di Serio south of Crema. Similar to all Lombardian rivers, it forms part of the Po drainage area.
Its valley is known as the Val Seriana.