The earliest people to inhabit this area were not here until about 11,000 years ago. The Park was favored during the Summer for hunting. The lodgepole pine which is abundant in the park was very useful for teepee poles. The area during this time was controlled by the Utes.

The area became part of the U.S. when the government bought it as part of the Louisiana Purchase in 1803. Early trappers avoided the area because of its tall threatening peaks in the expeditions. The first known settler was Joel Estes who brought his family there after he climbing with his son to the top of a tall peak and saw the beautiful valley below. Because of cold weather which cows could not survive well in, the Estes family sold the cows and bought oxen. After news of the beautiful valley spread, the Estes cabin became a guest accommodation.

In 1868 many people were becoming interested in the high peaks and began climbing them. One of the first climbers in the area was John Wesley Powell who reached the summit of Longs Peak in 1868.

Not only was this park home to tall peaks and beautiful views, but also large veins of silver and gold. The gold rush of Colorado took place in the 1870's and Lulu City became one of the big mining towns in the area. However, when the supply of minerals was found to be smaller than expected, the town was quickly deserted in the 3 years, costing the area dearly. Bear, deer, wolves and elk were very common in the area and were hunted regularly during the gold rush to support growing mining communities.

When F.O. Stanley built the Stanley Hotel in 1909, his efforts to preserve wildlife beauty in the area led to the establishment of the Protective and Improvement Association .

The area became the tenth National Park when Enos Mills who built a hotel and guided nature trips wanted to preserve the wildlands from inappropriate use. He wanted the beauty of the area to be there for many years to come. He worked from 1909 to 1915 in order to finally help the area become a National Park.

Today the park covers over 415 square miles. In 1990, expansion of the park was needed to include Lily Lake in its boundaries, so 465 acres were added.