The narrator begins with the claim that he is an "invisible man". His invisibility, he says, is not a physical condition—he is not literally invisible—but is rather the result of the refusal of others to see him. He says, because of his invisibility, he has been hiding from the world, living underground, and stealing electricity from the Monopolated Light & Power Company. He burns 1,369 light bulbs simultaneously and listens to Louis Armstrong’s “(What Did I Do to Be So) Black and Blue” on a phonograph. He tells the reader that he has gone underground in order to write the story of his life and invisibility.
As a young man, in the late 1920s or early 1930s, the narrator lived in the South. Because he is a gifted public speaker, he is invited to give a speech to a group of important white men in his town. The men reward him with a briefcase containing a scholarship to a prestigious black college, but only after humiliating him by forcing him to fight in a “battle royal” in which he is pitted against other young black men, all blindfolded, in a boxing ring. After the battle royal, the white men force the youths to scramble over an electrified rug in order to snatch at fake gold coins. The narrator has a dream that night in which he imagines his scholarship is actually a piece of paper reading, “To Whom It May Concern . . . Keep This Nigger-Boy Running".
Three years later, the narrator is a student at the college. He is asked to drive a wealthy white trustee of the college, Mr. Norton, around the campus. Norton talks incessantly about his daughter, then shows an undue interest in the narrative of Jim Trueblood, a poor, uneducated black man who impregnated his own daughter. After hearing this story, Norton needs a drink, and the narrator takes him to the Golden Day, a saloon and brothel that normally serves black men. A fight breaks out among a group of mentally imbalanced black veterans at the bar, and Norton passes out during the chaos. He is tended by one of the veterans, who claims to be a doctor and who taunts both Norton and the narrator for their blindness regarding race relations.
Back at the college, the narrator listens to a long, impassioned sermon by the Reverend Homer A. Barbee on the subject of the college’s Founder, whom the blind Barbee glorifies with poetic language. After the sermon, the narrator is chastised by the college president, Dr. Bledsoe, who has learned of the narrator’s misadventures with Norton at the old slave quarters and the Golden Day. Bledsoe rebukes the narrator, saying he should have shown the white man an idealized version of black life. He expels the narrator, giving him seven letters of recommendation addressed to the college’s white trustees in New York City, and sends him there in search of a job.
The narrator travels to the bright lights and bustle of 1930s Harlem, where he looks unsuccessfully for work. The letters of recommendation are of no help. At last, the narrator goes to the office of one of his letters’ addressees, a trustee named Mr. Emerson. There he meets Emerson’s son, who opens the letter and tells the narrator that he has been betrayed: the letters from Bledsoe actually portray the narrator as dishonorable and unreliable. The young Emerson helps the narrator to get a low-paying job at the Liberty Paints plant, whose trademark color is "Optic White". The narrator briefly serves as an assistant to Lucius Brockway, the black man who makes this white paint, but Brockway suspects the narrator of joining in union activities and turns on him. The two men fight, neglecting the paint-making; consequently, one of the unattended tanks explodes, and the narrator is knocked unconscious.
The narrator awakens in the paint factory’s hospital, having temporarily lost his memory and ability to speak. The white doctors seize the arrival of their unidentified black patient as an opportunity to conduct electric shock experiments. After the narrator recovers his memory and leaves the hospital, he collapses on the street. Some black community members take him to the home of Mary, a kind woman who lets him live with her for free in Harlem and nurtures his sense of black heritage. One day, the narrator witnesses the eviction of an elderly black couple from their Harlem apartment. Standing before the crowd of people gathered before the apartment, he gives an impassioned speech against the eviction. Brother Jack overhears his speech and offers him a position as a spokesman for the Brotherhood, a political organization that allegedly works to help the socially oppressed. After initially rejecting the offer, the narrator takes the job in order to pay Mary back for her hospitality. But the Brotherhood demands that the narrator take a new name, break with his past, and move to a new apartment. The narrator is inducted into the Brotherhood at a party at the Chthonian Hotel and is placed in charge of advancing the group’s goals in Harlem.
After being trained in rhetoric by a white member of the group named Brother Hambro, the narrator goes to his assigned branch in Harlem, where he meets the handsome, intelligent black youth leader Tod Clifton. He also becomes familiar with the black nationalist leader Ras the Exhorter, who opposes the interracial Brotherhood and believes that black Americans should fight for their rights over and against all whites. The narrator delivers speeches and becomes a high-profile figure in the Brotherhood, and he enjoys his work. One day, however, he receives an anonymous note warning him to remember his place as a black man in the Brotherhood. Not long afterward, the black Brotherhood member Brother Wrestrum accuses the narrator of trying to use the Brotherhood to advance a selfish desire for personal distinction. While a committee of the Brotherhood investigates the charges, the organization moves the narrator to another post, as an advocate of women’s rights. After giving a speech one evening, he is seduced by one of the white women at the gathering.
After a short time, the Brotherhood sends the narrator back to Harlem, where he discovers that Clifton has disappeared. Many other black members have left the group, as much of the Harlem community feels that the Brotherhood has betrayed their interests. The narrator finds Clifton on the street selling dancing “Sambo” dolls—dolls that invoke the stereotype of the lazy and obsequious slave. Clifton apparently does not have a permit to sell his wares on the street. White policemen accost him and, after a scuffle, shoot him dead as the narrator and others look on. On his own initiative, the narrator holds a funeral for Clifton and gives a speech in which he portrays his dead friend as a hero, galvanizing public sentiment in Clifton’s favor. The Brotherhood is furious with him for staging the funeral without permission, and Jack harshly castigates him. Jack rants about the Brotherhood’s ideological stance. The narrator accuses Jack of not understanding sacrifice. Jack removes a glass eye from one of his eye sockets. The narrator leaves shocked. The Brotherhood sends the narrator back to Brother Hambro to learn about the organization’s new strategies in Harlem.
The narrator leaves feeling furious and anxious to gain revenge on Jack and the Brotherhood. He arrives in Harlem to find the neighborhood in ever-increasing agitation over race relations. Ras confronts him, deploring the Brotherhood’s failure to draw on the momentum generated by Clifton’s funeral. Ras sends his men to beat up the narrator, and the narrator is forced to disguise himself in dark glasses and a hat. In his dark glasses, many people on the streets mistake him for someone named Rinehart, who seems to be a pimp, bookie, lover, and reverend all at once. At last, the narrator goes to Brother Hambro’s apartment, where Hambro tells him the Brotherhood has chosen not to emphasize Harlem and the black movement. He cynically declares that people are merely tools and the larger interests of the Brotherhood are more important than any individual. Recalling advice given to him by his grandfather, the narrator determines to undermine the Brotherhood by seeming to go along with them completely. He decides to flatter and seduce a woman close to one of the party leaders in order to obtain secret information about the group.
But the woman he chooses, Sybil, knows nothing about the Brotherhood and attempts to use the narrator to fulfill her fantasy of being raped by a black man. While still with Sybil in his apartment, the narrator receives a call asking him to come to Harlem quickly. The narrator hears the sound of breaking glass, and the line goes dead. He arrives in Harlem to find the neighborhood in the midst of a full-fledged riot, which he learns was incited by Ras. The narrator becomes involved in setting fire to a tenement building. Running from the scene of the crime, he encounters Ras, dressed as an African chieftain. Ras calls for the narrator to be lynched. The narrator flees, only to encounter men he initially thinks are policemen who want to know what's in his briefcase. In his attempt to evade them, the narrator falls down a manhole. The men mock him and pull the cover over the manhole.
The narrator says that he has stayed underground ever since; the end of his story is also the beginning. He states that he finally has realized that he must honor his individual complexity and remain true to his own identity without sacrificing his responsibility to the community. He says that he finally feels ready to emerge from underground.