Ifemelu, a Nigerian woman who lives in Princeton, New Jersey, gets her hair braided in preparation for her upcoming return to Nigeria. She has broken up with her boyfriend, Blaine, closed her popular blog about race, and uprooted her life because she feels weighed down. When she thinks of returning to Nigeria, she can’t help but think of Obinze, her first love, now a wealthy man in Lagos with a wife and daughter. Upon receiving an email from Ifemelu, Obinze becomes distracted. He has stumbled into wealth after his cousin introduces him to a well-connected man. His wife, Kosi, is beautiful and adoring, but they never connected on the emotional level that he and Ifemelu did. That night, he listens to the music he and Ifemelu used to listen to when they made love.
The novel flashes back to Ifemelu’s youth. She and Obinze meet at a party where a friend attempts to set Obinze up with a girl named Ginika. Obinze has admired Ifemelu from afar since transferring to their school, and they immediately hit it off. They date all throughout secondary school and through the start of university. However, university lecturer strikes keep closing the universities, and Obinze and Aunty Uju encourage Ifemelu to apply to school in America. Ifemelu is accepted and then quickly approved for a student visa. Ifemelu and Obinze plan to one day reunite in America. Unfortunately, Ifemelu’s student visa does not allow her to work, and without a full scholarship and stipend, Ifemelu must find a source of income. She applies to jobs using a family friend’s social security card to no avail. In desperation, she agrees to work for a shady tennis coach as his “relaxation assistant,” which involves allowing him to touch her sexually. After one meeting, she never returns to the coach. Out of shame and self-loathing, she stops replying to Obinze’s messages and emails.
Ifemelu’s luck changes when Ginika introduces her to Kimberly, a white woman who needs a babysitter. The steady work offers her a chance to focus on her studies. She meets Kimberly’s wealthy cousin, Curt, who is immediately smitten with her. They start dating, and when Ifemelu graduates, Curt helps her get a job that will sponsor her green card. For the job interview, Ifemelu needs to have her hair relaxed so that it will look professional according to American standards. The relaxer burns her scalp, and her friend Wambui encourages her to try wearing her hair natural. At first, Ifemelu thinks her hair is ugly, but soon grows to love it. One day, she runs into a friend from Nigeria, who asks what happened between her and Obinze. She gives him the cold shoulder, and is upset the rest of the day. Although she explains that the university friend was not an ex-boyfriend, Curt acts possessive.
Meanwhile, Obinze lives as an illegal immigrant in London. His American visa application was rejected because of anti-terror panic after the September 11, 2001 attacks. His mother offers to bring him as a research assistant on a trip to London as a way to get him into Britain. Obinze’s friend links him up with a fellow Nigerian, Vincent, who is willing to let him use his national insurance card in order to work if Obinze will give him a percentage of his income. Obinze agrees and finds a job in a warehouse. Eventually, Vincent demands more money. Obinze refuses, and the next day his boss tells him that someone reported him as an illegal immigrant. Desperate, Obinze tries to find someone to arrange a green card marriage for him. The day Obinze’s wedding is meant to take place, he arrives to the courthouse only to find the police awaiting him. Obinze is deported.
Ifemelu cheats on Curt and ends their relationship. After she writes an email to Wambui detailing her frustration with Curt’s inability to understand the necessity of Essence magazine in a world of beauty magazines catering to white women, Wambui suggests Ifemelu start blogging. Ifemelu starts a blog focusing on her observations on race in America as a non-American black woman, and her clever posts soon lead to its popularity. At a conference for minority bloggers, she runs into Blaine, a black American professor at Yale. They begin dating, and Ifemelu moves in with him. When Ifemelu does not attend a protest Blaine organizes against the university’s racial profiling of a black staff member, they have a major fight and almost break up. However, Barack Obama’s presidential candidacy draws them back together and gives them a joint mission up until the election, and Ifemelu’s subsequent decision to leave.
Aunty Uju calls Ifemelu to tell her that her son, Dike, tried to kill himself. Ifemelu rushes to be with him. Once she’s back in Nigeria, Ifemelu slowly finds her feet. However, she is hesitant to contact Obinze. Finally, she texts him, and he wants to meet up with her as soon as possible. Their attraction is still undeniable. When Obinze asks her why she cut him off, Ifemelu tells him the story of the tennis coach, surprised at her own tears. Obinze holds her hand, and she basks in the safety she feels. After more dates, Ifemelu awkwardly rekindles their sexual relationship, although she does not want to be his mistress. They argue, and Ifemelu calls Obinze a coward for not divorcing Kosi. Shaken, Obinze thinks about Ifemelu’s accusation, and finds truth in it. He asks Kosi for a divorce. Kosi tries to ignore his declaration, reminding him that he has a duty to his family. Obinze decides that he doesn’t want his daughter to grow up with her parents only playing the roles of happy husband and wife. Days later, he shows up at Ifemelu’s flat telling her that he has left Kosi, will continue to be present in his daughter’s life, and wants to be with Ifemelu. Ifemelu invites him in.