Osage Beach is a city in Camden and Miller counties in the U.S. state of Missouri, near the Lake of the Ozarks. Most of the city is in Camden …Osage Beach is a city in Camden and Miller counties in the U.S. state of Missouri, near the Lake of the Ozarks. Most of the city is in Camden County, while a small eastern sliver is in Miller County. The population was 4,637 at the 2020 census.