Walnut Hills is one of the 52 neighborhoods of Cincinnati, Ohio. One of the city's oldest hilltop neighborhoods, it is a large diverse area on the near east side of Cincinnati. The population was 6,344 in the 2020 census.

The neighborhood was named from the farm of an early settler, Reverend James Kemper, which he called Walnut Hill. For generations, the Kemper family lived in the Kemper Log House. Walnut Hills was annexed to the City of Cincinnati in September, 1869.

After the turn of the century, new migrants from Cincinnati's downtown basin moved to the area. Like South Avondale, Walnut Hills was home to many Jewish and Italian families. An area on the western side of McMillan St. was known as “Little Italy.” After construction of the Union Terminal, and other public housing projects demolished housing in the West End, many African Americans moved to the area in the 1930s. When modern suburbs were created after World War II, many of community's middle class white residents moved out of Walnut Hills. Similarly, middle class African Americans moved from the area after less affluent residents moved to the area. Almost 80% of Walnut Hills was populated by African Americans by 1970.

Walnut Hills is home to multiple historic sites. The Harriet Beecher Stowe House was where Harriet Beecher Stowe's father, Lyman Beecher, lived. Harriet spent time there since it was the center of Beecher family life in Cincinnati. While Harriet's husband was out of town her first children, twin daughters, were born in the house. Although Harriet wrote her famous anti-slavery novel in Brunswick Maine, the factual material for the novel was gathered during her almost 20 years in Cincinnati. Her father was the president of Lane Seminary where Harriet first learned about the horrors of slavery by attending the famous Lane Debates. These were a series of presentations, held at the seminary in 1834, about the need to abolish slavery.'

The Walnut Hills Library, Cincinnati's first Carnegie Library, and the Walnut Hills United Presbyterian Church's remaining tower at Taft and Gilbert were designed by architect Samuel Hannaford.

The commercial district at Peebles' Corner, originally called Kemper's Corner, was once the busiest district outside Downtown Cincinnati, with six street cars lines intersecting at McMillan and Gilbert by the end of the 19th century.

The original site of Walnut Hills High School is located in the neighborhood.

Several historic districts in Walnut Hills have been listed on the National Register. These include the Gilbert-Sinton Historic District, Gilbert Row, and Peeble's Corner Historic District.