The Grinch, a grouchy, cave-dwelling creature, hates Christmas; his only companion is his unloved but loyal dog, Max. He resides on the snowy Mount Crumpit, located north of the town of Whoville, home of the warm-hearted Whos.

From his cave, the Grinch can hear the noisy Christmas festivities that take place in Whoville. Continually annoyed, he devises a wicked scheme to steal their presents, trees, and Christmas food. Crudely disguised as Santa Claus and with Max as a reindeer, the Grinch rides a sleigh down the mountain to Whoville, where he begins to steal the Whos' Christmas presents, Christmas trees and decorations, and food. When briefly interrupted by Cindy Lou Who, the Grinch concocts a crafty lie to effect his escape. He then does the same thing to all the other houses in the village, filling his sleigh.

The Grinch then forces Max to pull the sleigh to the top of Mount Crumpit, intending to dump everything into the abyss. As dawn arrives, the Grinch expects the Whos to let out bitter and sorrowful cries, but instead, much to his shock, they sing a joyous Christmas song. This puzzles the Grinch, until it dawns on him that "maybe Christmas, perhaps, means a little bit more" than just presents and feasting. With this realization, the Grinch's shrunken heart suddenly grows three sizes, and he returns to Whoville bringing back all the Whos' belongings. The Grinch then participates in the Whos's Christmas feast.