| Native Name: | Grafschaft Sponheim-Sayn |
| Conventional Long Name: | County of Sponheim-Sayn |
| Common Name: | Sponheim-Sayn |
| Era: | Middle Ages |
| Status: | Vassal |
| Empire: | Holy Roman Empire |
| Government Type: | Principality |
| Year Start: | 1261 |
| Year End: | 1283 |
| Event Start: | Partitioned from Sponheim-Eberstein |
| Event End: | Partitioned in twain |
| P1: | Sponheim-Eberstein |
| S1: | Sayn |
| S2: | Sayn-Homburg |
Sponheim-Sayn was a county of Rhineland-Palatinate and North Rhine-Westphalia, Germany. It was created as a partition of Sponheim-Starkenburg in 1261, and it comprised the lands of the former county of Sayn. In 1283, it was divided into Sayn and Sayn-Homburg.