David Copperfield states his intention to tell the story of his life, beginning from the very moment of his birth. This takes place six months after the death of his father (also named David Copperfield). David's earliest memories are of a happy, makeshift family consisting of himself, his mother Clara, and the motherly housekeeper, Peggotty. When David is seven or eight years old, however, Clara begins to spend a great deal of time with a man named Mr. Murdstone, whom David instinctively dislikes and fears. Eventually, Peggotty takes David on a trip to see her brother, Mr. Peggotty, who is a fisherman in Yarmouth. David enjoys the visit—particularly Mr. Peggotty's niece, little Em'ly, whom David becomes infatuated with. When he and Peggotty return home, however, David learns that his mother and Mr. Murdstone have married, and that Mr. Murdstone's sister, Miss Murdstone, has come to live with them. Both Mr. and Miss Murdstone are bullies determined to have their way, and they use David as a pawn in their efforts to train Clara to behave "firmly."
The Murdstones spitefully send David away to a boarding school run by an abusive headmaster named Mr. Creakle. David's time at the school is not entirely unhappy, as he befriends Tommy Traddles, a kindhearted boy, and James Steerforth, an older, wealthy, and charismatic student who takes David under his wing. David's schooling ends abruptly, however, when he hears that both his mother and her new baby have died.
After Clara's funeral, Mr. Murdstone puts David to work in a London counting-house that he owns. David is miserable and longs to continue with his education. The one bright spot in his life is the Micawbers: an impoverished but good-natured family David lodges with. However, Mr. Micawber eventually moves his family to the country in the hopes of securing a job and digging himself out of debt. Now entirely alone, David decides to run away and throw himself on his great-aunt's mercy. After a difficult journey entirely on foot, David makes it to Dover and finds Miss Betsey's cottage. She is initially unsure of what to do with him, but when the Murdstones pay Miss Betsey a visit, she lectures them for abusing David and driving Clara to her death. Showing the Murdstones to the door, she then announces that she and Mr. Dick—a mentally disabled man who lives with her—will be David's guardians going forward.
Miss Betsey places David in a school run by a kindly, absent-minded man named Doctor Strong. Because the school is in Canterbury, David lodges with Miss Betsey's lawyer, Mr. Wickfield. David becomes good friends with Wickfield's daughter Agnes—a kind and patient girl who is devoted to her widower father. However, David is somewhat unnerved by the presence of Mr. Wickfield's clerk and apprentice, Uriah Heep, who has a cloying and self-deprecating demeanor.
One day, while passing through London, David runs into Steerforth. David visits Steerforth's home, where he meets both Steerforth's mother, Mrs. Steerforth, and a young, sarcastic woman named Rosa Dartle—Steerforth’s cousin, who has a scar on her face from a time when Steerforth threw a hammer at her. Steerforth then accompanies David to visit the Peggottys. While at Mr. Peggotty's, David learns that Emily is now engaged to her cousin Ham. Unfortunately, David does not notice that Emily doesn't seem especially happy about the engagement, or that both she and Steerforth seem taken with one another—even when Steerforth buys a boat and names it the Little Em'ly.
David takes up Miss Betsey's suggestion that he become apprenticed to a proctor. She takes him to meet a proctor named Francis Spenlow and then helps him find a room to rent in London. He eventually visits Agnes and learns that her home life is in disarray: Mr. Wickfield is now drinking more than ever thanks to the encouragement of Uriah, who has positioned himself to become Wickfield's partner.
David encounters Uriah himself shortly after this conversation and learns that he intends on marrying Agnes—something that makes David almost murderously angry. He is soon distracted, however, by falling deliriously in love with Mr. Spenlow's daughter, Dora—a sweet but pampered girl. He also reconnects with Traddles (now studying to be a lawyer and saving to marry his fiancée, Sophy Crewler) and Mr. Micawber, who is as plagued by financial difficulties as ever and has somehow roped Traddles into them.
David receives word that Peggotty’s husband, Barkis, is dying, so David travels to Yarmouth. After Barkis dies, his family discovers that he had managed to save up quite a bit of money, so Peggotty travels to London to sort out the will, with plans to meet David and her family at Mr. Peggotty's that night. Ham shows up late and distraught, with a letter from Emily explaining that she has run away with Steerforth in order to become a "lady." Mr. Peggoty and David travel to London to speak with Steerforth's mother, who is unsympathetic. She offers Mr. Peggotty money for the loss of his niece and complains bitterly of the rift Steerforth's actions have caused within her own family.
David returns to London to see Dora, and the two eventually become secretly engaged. Not long afterwards, David returns to his lodgings one evening to find Mr. Dick and Miss Betsey, who confesses that she is "ruined." Miss Betsey explains that she lost her money in a string of bad investments. Mr. Wickfield and Uriah Heep stop by later, and David is dismayed to see that Wickfield looks sicker and more beaten down than ever.
Although David is working harder than ever, his relationship with Dora suffers two setbacks. First, he tries to impress upon her that his financial circumstances have changed, and that it would therefore be helpful if she learned a bit about doing housework and keeping accounts—a suggestion that only upsets Dora. Worse yet, Mr. Spenlow angrily rejects his daughter's engagement. Shortly after this, Mr. Spenlow dies of a sudden "fit," and is revealed to have been deeply in debt at the time of his death.
On his aunt's request, David goes to Dover to see what is going on at her cottage, which is being let out. This gives David an opportunity to visit the Micawbers (Mr. Micawber now works for Uriah) and observe Uriah's influence on the Wickfield household firsthand: Mr. Wickfield is visibly enraged when Uriah brings up the possibility of marrying Agnes but also says he is powerless to do anything about his "torturer" Uriah and speaks bitterly of his own failings and weaknesses. Agnes, meanwhile, is increasingly sad and anxious but helpfully offers David advice on how to court Dora.
David and Traddles visit Dora's aunts, who agree to allow David to pay visits to Dora but not become engaged to her (at least not yet). Meanwhile, David learns of more "mischief" on Uriah's part: he has insinuated to Doctor Strong that his young wife, Annie, is having an affair with her cousin Jack Maldon—a misunderstanding only resolved years later, when Mr. Dick takes it upon himself to clear the air between Doctor and Mrs. Strong. What's more, David receives a letter from Mrs. Micawber saying that her husband has become cold and distant since he began working for Uriah.
Time passes, and David and Dora are finally able to marry. While the couple is generally happy together, it gradually becomes clear that David expects more of Dora than she can give him. David attempts to instruct her several times on how to run a household, but this distresses her, and he always gives up. Dora eventually becomes pregnant, but either miscarries or gives birth to a child that dies almost immediately. The experience weakens her physically, and David slowly comes to terms with the realization that his marriage will never meet his expectations.
Meanwhile, through Rosa Dartle and Steerforth's servant, Littimer, David learns that Steerforth eventually grew tired of Emily and attempted to marry her off to Littimer, but Emily escaped. David and Mr. Peggotty track down Martha Endell—a "fallen" woman Emily was once kind to—and ask her to be on the lookout for Emily. Martha eventually succeeds and leads Mr. Peggotty and David to Emily. Mr. Peggotty later informs David that he intends to take her with him to Australia to start a new life.
Shortly after this, David, Miss Betsey, and Traddles travel to Dover for a meeting that Mr. Micawber has requested. Agnes, Uriah, and Mrs. Heep are also present at this meeting. Mr. Micawber reveals everything he knows about Uriah Heep's underhanded dealings: that Uriah forced Micawber to work for him by loaning him money, and that Uriah encouraged Mr. Wickfield's alcoholism in order to blackmail him over a series of illegal business dealings Wickfield had ostensibly entered into (but which Uriah himself was in fact guilty of, having forged Mr. Wickfield's signature). Mr. Micawber explains that he has documents proving his claims, and Uriah is ultimately forced to relinquish total control of the partnership to Mr. Wickfield.
Soon, Dora dies, but David is too preoccupied dealing with the fallout from Mr. Micawber's revelations to properly mourn her death. The Micawbers are as impoverished as ever and have decided to seek their fortunes in Australia along with Mr. Peggotty, little Em'ly, Martha, and Mrs. Gummidge. Before David sees them off, he travels to Yarmouth to deliver a message from Emily to Ham. As David arrives in Yarmouth, a storm is blowing in from the sea, and he eventually learns of a shipwreck along the coast. When David travels down to the beach, he sees Ham hard at work trying to rescue those on board only to drown in the attempt. Not long afterwards, the body of one of the ship's passengers washes ashore, and David realizes it is Steerforth.
David spends roughly a year traveling around Europe in an attempt to recover and gradually comes to the realization that he is in love with Agnes. When David returns to England, Agnes and David resume their friendship and eventually declare their love for one another. They marry, and the narrative skips ahead ten years to a visit from Mr. Peggotty, who has achieved modest financial success as a farmer. He says that Emily did eventually learn about Ham’s death, but that she is generally doing well.
David closes his account by reflecting fondly on those closest to him—including Miss Betsey, Mr. Dick, Peggotty, and Traddles—and the role they continue to play in his life. He contrasts this with images of the superficial high society people like Jack Maldon inhabit, and with the mutual animosity and loss that binds Mrs. Steerforth and Rosa Dartle together. Above all, though, David is thankful for Agnes, and he prays that he will see her even as he dies, guiding him "upward."