Lake Waynoka is a census-designated place (CDP) and gated community in Brown County, Ohio, United States, located around a similarly named reservoir between Sardinia and Russellville.

[4] In 1970, American Realty Service Corporation of Memphis, Tennessee, began the development of Lake Waynoka by buying farm land, damming the headwaters of Straight Creek, a tributary of the Ohio River, and dividing the land into lots roughly one-third of an acre in size.

American Realty also created other lake communities.

Over the years, Lake Waynoka has transitioned from a weekend and summer get-away spot to a community of full-time residents with a high rate of continued growth.

Migration from Cincinnati and Dayton has helped continue this growth.