Larsmo (Luoto in Finnish) is a municipality of Finland.

It is located in the province of Western Finland and is part of the Ostrobothnia region. The municipality has a population of 4,251 (2003) and covers an area of 170.34 km² of which 32.59 km² is water. The population density is 25.0 inhabitants per km².

The municipality is unilingually Swedish.