Schmerikon has a population (as of ) of . , about 25.9% of the population was made up of foreign nationals. Of the foreign population, (), 22 are from Germany, 239 are from Italy, 363 are from ex-Yugoslavia, 17 are from Austria, 140 are from Turkey, and 97 are from another country. Over the last 10 years the population has grown at a rate of 8.2%. Most of the population () speaks German (83.4%), with Italian being second most common (4.7%) and Serbo-Croatian being third (3.2%). Of the Swiss national languages (), 2,654 speak German, 11 people speak French, 150 people speak Italian, and 1 person speaks Romansh.