According to the U.S. Census Bureau, the county has a total area of 1,254.73 square miles (3,249.7 km), of which 1,133.31 square miles (2,935.3 km) is land and 121.42 square miles (314.5 km) (9.68%) is water. It is the largest county by land area in South Carolina. The highest point in the county is 124 feet (38 m) above sea level.

Horry County is in the northeastern corner of South Carolina. It is a diverse land made up of rivers, beaches, forests, and swamps, and is bordered by the Atlantic Ocean to the east, the Little Pee Dee River and Drowning Creek (also known as the Lumber River) on its western side, and North Carolina to the north. The Waccamaw River, around 140 miles (230 km) long, runs through southeastern North Carolina and eastern South Carolina into Horry County. The river runs through the coastal plain, along the eastern border between the two states, and into the Atlantic Ocean.

• Waccamaw National Wildlife Refuge (part)

• Cartwheel Bay Heritage Preserve/Wildlife Management Area
• Conway Post Office
• Heritage Shores Nature Preserve
• Horry County Museum
• Lewis Ocean Bay Heritage Preserve/Wildlife Management Area
• Myrtle Beach State Park
• North Myrtle Beach Area Historical Museum
• Russell Burgess Coastal Preserve
• Waccamaw River Heritage Preserve/Wildlife Management Area

• Atlantic Ocean (North Atlantic Ocean)
• Calabash River
• Dunes Lake
• Great Pee Dee River
• Intracoastal Waterway
• Lake Busbee
• Little Pee Dee River
• Little River
• Long Bay
• Lumber River
• Murrells Inlet
• Tuckahoe Bay
• Waccamaw River

• Columbus County, North Carolina – northeast
• Brunswick County, North Carolina – east
• Georgetown County – southwest
• Marion County – west
• Dillon County – northwest

As of the 2020 census, 351,029 people, 140,260 households, and 89,281 families were residing in the county.

At the 2010 census, 269,291 people, 112,225 households, and 72,254 families resided in the county. The population density was 237.5 inhabitants per square mile (91.7/km). The 185,992 housing units averaged 164.0 per square mile (63.3/km). The racial makeup of the county was 79.9% White, 13.4% Black or African American, 1.0% Asian, 0.5% American Indian, 0.1% Pacific Islander, 3.1% from other races, and 2.0% from two or more races. Those of Hispanic or Latino origin made up 6.2% of the population. In terms of ancestry, 15.3% were American, 13.4% were African American (which can include other ethnicities), 13.3% were Irish, 12.8% were German, 11.3% were English, and 6.1% were Italian.

Of the 112,225 households, 27.3% had children under 18 living with them, 47.2% were married couples living together, 12.5% had a female householder with no husband present, 35.6% were not families, and 26.8% of all households were made up of individuals. The average household size was 2.37, and the average family size was 2.84. The median age was 41.1 years.

The median income for a household in the county was $43,142 and for a family was $51,608. Males had a median income of $37,351 versus $29,525 for females. The per capita income for the county was $24,811. About 11.6% of families and 16.1% of the population were below the poverty line, including 25.2% of those under age 18 and 7.5% of those age 65 or over.

Horry County has a South Carolina House of Representatives delegation made up of 10 state representatives. In addition, the county has a South Carolina Senate delegation made up of five state senators. The delegations work concurrently to represent county issues in Columbia.

The county's State House of Representatives delegation is currently made up of:

The county's State Senate delegation is currently made up of:

The county council of Horry County consists of members who represent 11 single-member districts with a chairman voted at-large. The county council meets at the Horry County Government and Justice Center in the first week of every month. Patricia S. Hartley is the clerk to council, members of the county council include:

The Horry County Police Department provides 24-hour services to the unincorporated areas of the county. It is the only county police department in South Carolina. The Horry County Sheriff's Office is responsible for courthouse security, processing of warrants, fingerprinting, registration of sex offenders, funeral escorts, background checks, and managing the J. Reuben Long Detention Center. The South Carolina Highway Patrol has a Troop 5 barracks in Conway, and provides services throughout the county. Myrtle Beach, Conway, Briarcliffe Acres, Atlantic Beach, Surfside Beach, Loris, and Aynor all have their own police departments, which patrol within the relevant town or city's border. North Myrtle Beach has a Public Safety Department, which provides police and fire services in the city of North Myrtle Beach.

In March 2020, Todd Cox, a former Horry County police officer, was fined $300 for failing to investigate reports of sex crimes against children. He and three other officers had been indicted in 2016 on charges of coercing sex and ignoring cases.

Horry County used to be loyally Democratic, even by the standards of the Solid South. In 1936, Republican candidate Alf Landon did not receive a single vote in Horry County. In 1964, though, Barry Goldwater carried the county by a margin almost as large as John F. Kennedy's 1960 margin. It has voted Republican in every election since, with the exception of supporting the third-party candidacy of Alabama Governor George Wallace in 1968 and neighboring Georgia's Jimmy Carter in 1976. While conservative Democrats continued to hold most local offices into the 1990s, today, there are almost no elected Democrats left above the county level. No Democratic presidential candidate has received more than 40% of the county's vote since 2000.

In 2022, the GDP was $18.3 billion (about $45,922 per capita), and the real GDP was $15.3 billion (about $38,472 per capita) in chained 2017 dollars.

In 2013, PTR Industries, a gunmaker, relocated to the Cool Springs Business Park near Aynor from Bristol, Connecticut. That state had passed restrictive gun control legislation following the Sandy Hook Elementary School shooting.

Twenty-one PTR employees relocated from Bristol. The company stated that it would hire an additional 30 workers in the first quarter of 2014, with a goal of having 120 employees by 2017.

As of April 2024, some of the largest employers in the county include Adidas, the city of Myrtle Beach, Coastal Carolina University, Food Lion, Hilton Grand Vacations, Publix, and Walmart.

• Conway–Horry County Airport (HYW) - Conway
• Grand Strand Airport (CRE) - North Myrtle Beach
• Green Sea Airport (S79) - Green Sea
• Myrtle Beach International Airport (MYR) - Myrtle Beach
• Twin City Airport (5J9) - Loris

• The Coast RTA bus system operates seven days a week, 364 days a year, on 15 routes throughout the Horry County/Grand Strand area, including Myrtle Beach, North Myrtle Beach, Surfside Beach, Garden City, Conway, Loris, and Aynor.

• Conway (county seat)
• Loris
• Myrtle Beach (largest community)
• North Myrtle Beach

• Atlantic Beach
• Aynor
• Briarcliffe Acres
• Surfside Beach

• List of counties in South Carolina
• National Register of Historic Places listings in Horry County, South Carolina
• Horry County Schools
• Waccamaw Indian People, state-recognized tribe that resides in the county
• 2023 Chinese balloon incident, high-altitude balloon shot down over the Atlantic Ocean, east of the county
• Myrtle Beach Speedway

• Horry County, South Carolina, 1730-1993, Catherine Heniford Lewis, University of South Carolina Press, 1998, ISBN 1-57003-207-6

Wikimedia Commons has media related to Horry County, South Carolina.

• Geographic data related to Horry County, South Carolina at OpenStreetMap
• Official website
• Horry County Schools