| 2009–10 National League B | |
| League: | National League B |
| Sport: | Ice hockey |
| No Of Teams: | 10 |
| Season: | Regular season |
| Season Champs: | EHC Visp |
| Season Champ Name: | Best record |
| Second Place: | EHC Olten |
| Top Scorer: | Dominic Forget |
| Playoffs: | Playoffs |
| Finals Champ: | Lausanne HC |
| Finals Runner-Up: | EHC Visp |
| Prevseason Link: | 2008–09 National League B season |
| Prevseason Year: | 2008–09 |
| Nextseason Link: | 2010–11 National League B season |
| Nextseason Year: | 2010–11 |
The 2009–10 National League B season was the season played in the National League B, Switzerland's second-tier professional ice hockey league, during 2009 and 2010. EHC Visp won the regular season championship, with a one point edge over second place EHC Olten. The winner of the playoffs was Lausanne HC, the third-ranked team of the regular season.