The area was inhabited for thousands of years by Native Americans including the Tachi Yokuts tribe.

An 1805 expedition probably led by Spanish Army Lieutenant Gabriel Moraga recorded discovering the river, which they named El Rio de los Santos Reyes (River of the Holy Kings) after the Three Wise Men of the Bible.

[8] In 1880, a dispute over land titles between settlers and the Southern Pacific Railroad resulted in a bloody gun battle on a farm 5.6 mi (9.0 km) northwest of Hanford; seven men died.

In 1928, oil was discovered in the Kettleman Hills located in the southwestern part of Kings County.

Ultimately, the federal government intervened to force both sides to negotiate a settlement.

[11] Lemoore Army Airfield was established for training and defense during World War II.

The completion of the California Aqueduct in the early 1970s brought needed water for agriculture and domestic use to the west side of the county.

Table Mountain is the highest point in Kings County at an elevation of 3,476 feet (1,059 m).

According to the California Department of Corrections and Rehabilitation, there were 18,640 inmates in Kings County prisons on March 31, 2010, which was 12.2% of the population.

In addition to the prosecution duties of the District Attorney, the Kings County District Attorney also has civil and criminal investigative authority with its own Bureau of Investigations composed of sworn peace officers with arresting authority.

[42] According to the Kings County Election Office, as of March 24, 2017, 51,323 residents were registered to vote.

In November 2008, Kings County voted 73.7% for Proposition 8 which amended the California Constitution to define marriage as between one man and one woman.

[46] The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense.

Other major agricultural commodities included pistachios, cotton, cattle and calves, almonds and processing tomatoes.

[49][50] Another major employer is NAS Lemoore, the U.S. Navy's newest and largest master jet base.

According to a Navy study in 2008, payroll, base spending, retiree and veterans' checks total more than $1 billion in annual economic impact to the region.

[51] Other important employers include a Del Monte Foods tomato processing plant, Adventist Health, the J. G. Boswell Company, an Olam International tomato processing facility, Leprino Foods, the largest mozzarella cheese maker in the world, the Kings County Government and the California Department of Corrections and Rehabilitation which operates three state prisons in Kings County.

[52] In 2011–2013, the U.S. Census Bureau estimated that the median household income in the county was $47,035 and that 17.6% of the population was below the poverty line.

In Kings County's case, the U.S. Census Bureau's estimated population of 151,366 was used for that calculation.

[33] According to Zillow Real Estate Research, an estimated 24% of homeowners in the county owned their homes free and clear in the third quarter of 2012.

[58] Jeffrey Michael, director of the Business Forecasting Center at the University of the Pacific, stated in an October 2010 newspaper interview that nearly half of Kings County's personal earnings come from government jobs, which pay more than agricultural employment.

Van Dam was quoted that month as saying that at current prices, dairy operators are at or close to the break-even point.

[61] By the summer of 2012, it was reported that despite a milk price of about $15 per hundredweight, the rising cost of cattle feed had caused many dairy farmers to sell all or part of their herds and even file for bankruptcy.

[66] The event returned as Kings County Homecoming Week in 2016 but without the traditional parade.

The privately owned airport in Avenal is the home of the Central California Soaring Club.