For more than 11,000 years, people have occupied a portion of the area that Richland now encompasses.

For centuries, the village of Chemna stood at the mouth of the Tapetett River, a Sahaptin name for the Yakima River, also called Tapteal. At Chemna, Sahaptin-speaking Wanapum, Walla Walla and Yakama Indians fished for seasonal runs of salmon and hunted small game, deer and antelope. They gathered berries, greens and root vegetables along the water and on the nearby hills.

In 1805, Captain William Clark of the Lewis and Clark Expedition ventured with two other men up the Columbia River to the mouth of the Yakima. The first white settlers arrived several decades later when the John B. Nelson family attempted to settle, in 1864, on the south side of the Yakima River. Within a year, they had moved up the valley. Benjamin and Mary Rosencrance arrived in 1880, living first on the south side and moving in 1888 to the north side of the river where they filed a homestead claim for 1,700 acres.

In 1892, Nelson Rich and Howard Amon formed the Benton Land and Water Company and located the town that would become Richland. The first post office opened here in 1905, listing the town’s name as Benton. At the request of the postal service, the town was soon renamed "Richland" to avoid confusion with another Washington community.  In 1910, Richland was incorporated as a Fourth Class City. Residents elected J. W. Randall as the first mayor.

For many years, Richland was a small, sleepy farming village. Then in 1942, the federal government saw Richland’s remote location, abundant water supply and mild weather as the right combination it needed for a portion of its Manhattan Project. Modern day Richland was born. Almost overnight, the village of 247 people developed into a federally owned town of 11,000 residents, nearly all of whom were employed at the Hanford Project. Thousands of workers from across the nation converged on the area surrounding Richland to construct facilities where plutonium for the world's first nuclear weapons would be created.

In 1958, Richland was incorporated as a chartered First Class City, transforming itself from a federally controlled Atomic Energy Community to a city governed by self-rule. Incorporation did not alleviate Richland's dependency on the federal Hanford facility. Rather, the city’s population continued to climb as Hanford transitioned into weapons production during the Cold War years. Now, many Richland residents are employed at the Hanford site in its environmental cleanup mission.

Through the years, Richland has become a full service city, providing general government services including police and fire protection, water, waste and electric utilities, parks and recreational activities, maintenance of city streets and public facilities, and library services. The city also pursues community and economic development and offers housing assistance.

Richland’s primary goal during the early years of the 21st century is to diversify its economy and job base away from Hanford. To that end, the Richland City Council adopted this vision statement in 2004: "Richland is a progressive, safe and family-friendly community that welcomes diversity.  It is noted for excellence in technology, medicine, education, recreation, tourism, and citizen participation.  This dynamic city, situated on two rivers, actively supports opportunities for economic development that are in harmony with the area's unique natural resources."

Richland continues to grow. The State of Washington identified Richland's 2007 population as 45,070 residents.