The Kitchen God's Wife opens with the narrative voice of Pearl Louie Brandt, the American-born daughter of a Chinese mother and a Chinese-American father, who is a speech therapist living in San Jose. Pearl's mother, Winnie Louie, has called Pearl up to request that Pearl ask her daughters to attend the engagement party of Pearl's cousin Bao-Bao in San Francisco. Right away, Pearl feels a reluctance to oblige her mother, since she is more involved in her American identity—perhaps a result of her marriage to Phil, an American—than her Chinese background. Nevertheless, she feels an obligation to attend her families' festivity and knows she would feel guilty otherwise. Then, two days before the engagement party, Pearl receives another call from her mother telling her that Auntie Du has died and that the funeral will be arranged for the day after the engagement party. So, with all of this on her shoulders, Pearl sets out toward San Francisco with her young daughters, Tessa and Cleo, and her husband.

Upon her return to her childhood home, Pearl's Auntie Helen, Bao-Bao's mother, who co-owns a flower shop with Pearl's mother, pulls Pearl aside and makes a request. Auntie Helen tells Pearl that Pearl must tell her mother Winnie about Pearl's multiple sclerosis, which everyone in the family knows about, except for Winnie. Helen says that Pearl must do this because Helen believes that Helen has a malignant brain tumor and does not want to die knowing that Winnie does not know this about her daughter. Helen continues by saying that if Winnie will not tell her mother the truth, Helen will be forced to do so herself. Later, Helen pulls Winnie's mother aside as well and tells Winnie that she must unveil the secrets of her past to her daughter because she cannot go to her grave with such secrets. We find out later that Helen knows her tumor is benign and is simply using the idea of her own death as a pretext to force mother and daughter to unleash their secrets.

It is at this point that the novel changes narrative voices and begins to be narrated by Winnie Louie, who begins to tell Pearl the story of Winnie's past. Before she reached the United States, Winnie experienced much turmoil, strife, and suffering. She was abandoned by her mother as a young child, never knowing very much about her mother's mysterious disappearance. Winnie, whose name in China was Weili, is forced to live with her Uncle and his two wives (New Aunt and Old Aunt). She never feels as loved as her uncle's true daughter, Weili's cousin, Peanut. Nevertheless, when the time comes, Winnie's aunts arrange a traditional marriage for her, and her father provides a large dowry, since he is an educated and well-established man. The marriage, however, to a man named Wen Fu, turns out to be a terrible one. Wen Fu is horribly abusive—physically, mentally, and emotionally. Winnie manages to suffer through her manage while surviving World War II. She loses many children along the way, some to early deaths and one that was stillborn. It is during the War that Winnie becomes friends with Helen, whose name in China was Hulan. By telling her daughter about this friendship, Winnie is revealing that Helen and Winnie are not really in-laws as the family in America believes, but only friends who have gone through much hardship together. Winnie had had to lie and say that Helen was her dead brother's first wife in order to bring Helen to the United States, after Winnie had already been in the United States for a while. Winnie lived her new husband Jimmy Louie, the man whom Pearl had always been told was her father. Jimmie Louie was a good husband, a good father, and a minister in the Chinese Baptist Church, but he had died when Pearl was a teenager.

Winnie had met Jimmy Louie in China, at an American dance. He was American born, though his background was Chinese, and he was extremely kind. The two fell in love, and Pearl escaped with him, after running away from Wen Fu. The biggest secret, however, that Winnie tells her daughter, is that before Winnie was able to escape her marriage, Wen Fu raped her and that Wen Fu is Pearl's real father. Winnie tells her daughter also that it is only now that she feels truly free from Wen Fu's wickedness and his threats, because she has received news of his death.

After Winnie tells her daughter about her past, Pearl reveals the secret of her own disease. By the time the wedding of Bao-Bao comes around, mother and daughter know each other better and are able to appreciate each other's positions, ideas, and beliefs better. Also, by the end of the novel, Helen reveals the planning of a trip to China—a trip that Helen, Pearl, and Winnie will take together.