The story of Orlando spans over 300 years (1588–1928). During this time, Orlando ages only thirty-six years, and changes gender from a man to a woman.

This fantastic story opens with the protagonist, Orlando, a young noble boy, pretending to chop off the heads of Moors, just like his father and grandfather have done. He is too young to fight, but he longs to go on adventures around the world like his family. Young Orlando goes out into the woods to write poetry and he falls asleep. He is awakened by trumpets sounding that the Queen Elizabeth has arrived. Orlando runs to his house to get ready. When the Queen sees him, she is impressed by his youth and innocence. Two years later, she sends for him to come to her court. There, she makes him Steward, Treasurer, and her lover, giving him all the wealth and status he could want. But when she sees Orlando kissing a young girl, she becomes furious and smashes her mirror with a sword.

For a while, Orlando takes to spending time with people of a "low kind." He frequents pubs and has his way with many young women. When he grows tired of this lifestyle, he heads back to the Court, this time under King James I (Queen Elizabeth has died). He dates many pretty and wealthy women, and becomes engaged to Euphrosyne, a woman of incredibly high birth and connections. This is the winter of the Great Frost and King James has turned the frozen river into a carnival scene. One night on the river, Orlando sees a figure skate past him. He is not sure whether it is a man or a woman, but he is incredibly attracted to it. It turns out to be the Russian princess, Sasha. Because Orlando speaks fluent French, he is the only one who can converse with her. They grow very close, become lovers, and plan to run away together. One day, Orlando sees her on the knee of a Russian sailor and he grows very angry. She assures him that nothing at all is going on. They plan to leave London together that night, but Orlando waits for Sasha and she never arrives. Orlando rides to the river to find that the frost has broken; hundreds of people are stranded on icebergs and he watches as the Russian ship drifts away.

Heartbroken, Orlando closes himself up inside his house with 365 rooms and fifty-two staircases. He decides that he will concentrate all his efforts on writing. He invites Nick Greene, a famous poet, to his house, and although Nick is entertaining, their difference in class is clearly a great barrier between them. When Nick returns home, he writes a parody of Orlando, a rich nobleman closed up inside his house. Orlando is once again heartbroken and he burns all his poems and dramas save one, a poem entitled "The Oak Tree." Orlando decides to refurnish every room in his home; after this is done, he invites all the neighbors in, earning their respect. One afternoon, he sees a figure on horseback in his courtyard. It is an extremely tall woman, the Archduchess Harriet of Romania. Orlando is repulsed by her advances toward him. He decides to leave England immediately.

King Charles II sends Orlando to Constantinople as an ambassador. There, he does such a good job that King Charles makes him a duke. That night, witnesses see Orlando lowering a rope down from his balcony, pulling up a woman, and embracing her passionately. The next morning, his servants find Orlando alone in his room, in a trance, unable to be awakened. On his desk they find a marriage certificate between Orlando and Rosina Pepita, a Spanish dancer. An insurrection occurs in Turkey and many foreigners are killed. Robbers break into Orlando's room, but since he is in a trance, they think he is already dead. After seven days, Orlando awakens from the trance a woman. She is not surprised, and it does not take her long to get used to her new body. Orlando rides away with Rustum, an old gypsy and joins Rustum's tribe in the mountains of Turkey. There, she feels at one with nature, but the gypsies mistrust Orlando because she values strange things like houses, bedrooms, and nature. Orlando decides to leave them and sail back to England.

On the ship voyage back to England, Orlando becomes romantic with the ship's Captain, Nicholas. Finally she feels what it is like to be a woman, and she cannot decide which gender she enjoys more. On returning to England, Orlando meets Archduchess Harriet again, but she finds out that he is really a man, Archduke Harry. He proposes to Orlando, but she finds him too slow and boring to marry. Orlando takes to spending time with famous poets of the eighteenth century like Addison, Dryden, and Pope. But she soon tires of them too, and begins spending time with some London prostitutes, whose stories she finds entertaining. As Orlando looks up to the sky above, she sees great clouds come over London; the eighteenth century is over and the nineteenth century has begun.

The Victorian era is gloomy; no sunlight gets in and all the vegetation is overgrown. Orlando feels pressure to yield to "the spirit of the age" and find a husband. She goes out and thinks herself nature's bride, a woman married to the moor. She falls and twists her ankle. Just then, a man rides up to rescue her: Marmaduke Bonthrop Shelmerdine, Esquire. Within two minutes, they know everything about each other, and know they are meant to be together. Orlando cannot believe that Shel has all the good qualities of a woman, and Shel cannot believe that Orlando has all the good qualities of a man. But Shel is a seaman, and when the wind changes, he must leave to do his duty on his ship. Before he goes, he marries Orlando in a hasty but romantic ceremony.

Orlando finally finishes the manuscript of her poem, "the Oak Tree," and she travels to London. There she meets Nick Greene, who is now the most eminent Victorian literary critic. He reads her poem and is very impressed by it; he promises to have it published with excellent reviews. It is now 1901, and as King Edward VII succeeds Queen Victoria on the throne, the world becomes much brighter, if more desperate. Suddenly a light becomes very bright, and Orlando is struck ten times on the head. It is 10 AM on Thursday, October 11, 1928; Orlando has been struck by the present; she is thirty-six. Orlando goes to the store, smells a candle, and thinks it is Sasha. She realizes that everything is now connected to something else. On the drive home from the store, Orlando thinks about all the different selves that compose her. She calls for the one that is the real Orlando, and then realizes that it is all of them.

The present frightens Orlando. She goes out to her oak tree to bury her book, but decides against it. She looks out over her house, thinking how it now belongs to history as well as to herself. She thinks that her husband's ship is safe and she cries out his name. Then Orlando sees the dead Queen coming once again to visit her house. She hears an airplane above and bears her breast to the sky. Shel, now a fine sea captain, leaps down. As he does this, a wild bird springs up. The clock strikes midnight, and it is the present.