Lappi () is a former municipality of Finland.
It was located in the province of Western Finland and was part of the Satakunta region. The municipality had a population of 3,236 (2003) and covered an area of 213.27 km<sup>2</sup> of which 7.24 km<sup>2</sup> is water. The population density was 15.2 inhabitants per km<sup>2</sup>.
The municipality was unilingually Finnish. UNESCO World Heritage Site Sammallahdenmäki is located in Lappi.
Lappi was consolidated with the city of Rauma on 1 January 2009, was officially disbanded and since has been considered a neighborhood.