Brian McKinney recorded the intense moment on his cell phone when he and his hiking partner came upon the big cat.
In the video, the mountain lion can be seen sitting completely still as it perches above the High Sierra trail. McKinney and his hiking partner, Sam Vonderheide, are heard discussing how to get away safely.
As the wild animal continued to stand its ground, the pair eventually chose to back away slowly, and the lion didn't chase them.
Wildlife biologist Daniel Gammons told ABC-owned station KFSN the men did the right thing by staying calm.
Gammons said people should make themselves appear larger by waving their arms overhead to scare off the animal, as the men did.
"The big thing these visitors did right was that they didn't panic and run," Gammons said. "Probably the most important message to get out to visitors is not to act like prey if they encounter a mountain lion."
ABC-owned television station KFSN contributed to this report.