The fire had grown to about 1.9 square miles (4.8 square kilometers) by Saturday evening.
A fierce windstorm ripped through the grove a year-and-a-half ago and toppled 15 giant sequoias, along with countless other trees.
The downed trees, along with massive numbers of pines killed by bark beetles, provided ample fuel for the flames.
The park has used prescribed burns to clear brush around the sequoias, which helps protect them if flames spread farther into the grove.
Meanwhile, most evacuation orders were lifted Saturday in the Sierra foothills about 80 miles (128 kilometers) to the northwest of the Yosemite fire, where a fire broke out on July 4. The Electra Fire that began near Jackson was mostly contained, and only areas directly within the fire's perimeter remained under evacuation orders, according to the California Department of Forestry and Fire Protection.