Nearly everything we know of Kempe's life is known from her Book. In the early 1430s, despite her claims to illiteracy, Kempe decided to record her spiritual autobiography. In the preface to the book, she describes how she employed as a scribe an Englishman who had lived in Germany, but he died before the work was completed and what he had written was unintelligible to others. She then persuaded a local priest to begin rewriting on 23 July 1436, and on 28 April 1438 he started work on an additional section covering the years 1431–4.
The narrative of Kempe's Book begins just after her marriage, and relates the experience of her difficult first pregnancy. After describing the demonic torment and Christic apparition that followed, Kempe undertook two domestic businesses: a brewery and a grain mill (both common home-based businesses for medieval women). Both failed after a short period of time. Although she tried to be more devout, she was tempted by sexual pleasures and social jealousy for some years. Eventually turning away from her vocational choices, Kempe dedicated herself completely to the spiritual calling that she felt her earlier vision required. Striving to live a life of commitment to God, Kempe in the summer of 1413 negotiated a chaste marriage with her husband. Although Chapter 15 of The Book of Margery Kempe describes her decision to lead a celibate life, Chapter 21 mentions that she is pregnant once again. Kempe gives birth to a child, her last, during her pilgrimage, and later relates that she brought a child with her when she returned to England. It is unclear whether the child was conceived before the Kempes began their celibacy, or in a momentary lapse after it.
Sometime around 1413, Kempe visited the female mystic and anchoress Julian of Norwich at her cell in Norwich. According to her own account, Kempe visited Julian and stayed for several days; she was especially eager to obtain Julian's approval for her visions of and conversations with God. The text reports that Julian approved of Kempe's revelations and gave Kempe reassurance that her religiosity was genuine. However, Julian did instruct and caution Kempe to "measure these experiences according to the worship they accrue to God and the profit to her fellow Christians." Julian also confirmed that Kempe's tears are physical evidence of the Holy Spirit in soul. Kempe also received affirmation of her gifts of tears by way of approving comparison to a Continental holy woman. In Chapter 62, Kempe describes an encounter with a friar who was relentless in his accusation for her incessant tears. This friar admits to having read of Marie of Oignies and now recognises that Kempe's tears are also a result of similar authentic devotion.
In 1438, the year her book is known to have been completed, a "Margueria Kempe," who may have been Margery Kempe, was admitted to the Trinity Guild of Lynn. It is not known whether this is the same woman, however, and it is unknown when or where after this date Kempe died.