Garfield County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 61,685. The county seat is Glenwood Springs, and the largest community is Rifle. The county is named in honor of United States President James A. Garfield.

Garfield County is included in the Rifle-Glenwood Springs Micropolitan Statistical Area, which also includes neighboring Pitkin County and is home to nearly 80,000 residents. The county is also included in the Glenwood Springs-Edwards combined statistical area.

As was the case in much of western Colorado, Garfield County historically belonged to the Ute people. For much of the 19th century, this land was guaranteed to the Ute peoples by Treaty with the United States government. The native inhabitants of the area were largely removed and sent to reservations in the early 1880s in the wake of the Meeker Massacre, in which a band of Ute members attacked the Indian agency on their reservation near the modern-day town of Meeker, killing 11 employees, including Indian agent (and town namesake) Nathan Meeker. This removal opened up vast swaths of western Colorado to white settlement.

Garfield County was founded on February 10, 1883, named in memory of President James A. Garfield, who was assassinated in September 1881. In April 1883, the town of Carbonate was incorporated and named the county seat. However, this was short-lived; Carbonate's remote location, difficult access, and severe winter weather made the town essentially impassable for much of the year. After just a few months, the city of Glenwood Springs was named the new county seat. Carbonate's post office closed in 1886, and by 1890, the town was completely abandoned.

In 1887, the Denver & Rio Grande Railroad arrived in Glenwood Springs, further fueling settlement and commerce in the surrounding area. Also in 1887, construction began on the Glenwood Hot Springs Resort, after the hot springs and vapor caves had been purchased by Walter Devereaux for $125,000 (equivalent to $4.25 million in 2025). In yet a third notable event to occur in 1887, the notorious old west gunslinger Doc Holliday died in Glenwood Springs from tuberculosis; a walking trail leading to his grave site remains a prominent tourist attraction in the city.

In 1896, a methane gas explosion in the Vulcan Mine on the Grand Hogback, near the town of New Castle, killed 49 workers and started a coal fire which still burns to this day. The mine eventually reopened, but suffered another explosion in 1913, killing an additional 37 workers. These underground coal fires have led the part of the Grand Hogback near the mine to be dubbed "Burning Mountain".

In 1904, US President Theodore Roosevelt went on a three-week bear hunt in Garfield County, an account of which was published in three 1905 issues of Outdoor Life Magazine. In 1905, the area was once again the target of old west gunslingers, as the outlaw Kid Curry and two accomplices robbed a train three miles west of the town of Grand Valley (now known as Parachute).

The county (specifically the city of Glenwood Springs) was one of the first areas in the United States to install electric lights. Some of the first in the area were installed inside the Fairy Caves of Iron Mountain, now part of Glenwood Caverns Adventure Park. The county was also the site of the first hydroelectric plant constructed in Colorado, built at Rifle Falls State Park in 1910. The plant changed the flow of the falls from one large waterfall to the three distinct falls seen today.