Izumi Shikibu was the daughter of Oe no Masamune, governor of Echizen. Her mother was the daughter of Taira no Yasuhira, governor of Etchu. At the age of 20 she was married to Tachibana no Michisada, who soon became governor of Izumi.As is standard for Heian period women, her name is a composite of "Izumi" from her husband's and her father's official designation of . Their daughter Koshikibu no Naishi was also a gifted poet. Izumi Shikibu accompanied Michisada to the provinces for a time, but found life there disagreeable and returned to the capital.

Izumi Shikibu had a sequence of affairs at the court in the capital. In the beginning, before her marriage to Michisada, she is believed to have been the companion (some accounts say wife) of a man named Omotomaru at dowager Queen Shoko's court. While still married to Michisada, she fell madly in love with Emperor Reizei's third son, Prince Tametaka (977–1002) and had a public affair; as a result of the scandal she was divorced by her husband and disinherited by her father. That Tametaka died because he visited Shikibu during the plague season became the prevailing mythology of this affair.

After Tametaka's death, she was courted by Prince Atsumichi (981–1007), a half brother of Tametaka. The first year of this affair is described in the semi-autobiographical novel ; like many of this period, the narration in Izumi Shikibu Nikki is in the third person, and parts of it are certainly fiction. It is believed that Shikibu's motive in writing this diary was partly to explain her affair to her fellow courtiers. Like before with Tametaka, this affair also soon ceased to be secret, and Atsumichi's real wife left his house in anger. Shikibu moved into Atsumichi's residence, and the two had a very public courtship until Atsumichi's death in 1007 at the age of 27.

The following year, Izumi Shikibu went to the court of Fujiwara no Shoshi, the daughter of Fujiwara no Michinaga and the Empress Ichijo. Izumi Shikibu Nikki was actually written around this time, along with most of her important work that is present in the and the Imperial anthologies. Her life of love and passion earned her the nick name of from Michinaga. Indeed, her poetry is characterised by overflowing passion and overwhelming sentimental appeal. Her style was the direct opposite of that of Akazome Emon, even though both served in the same court and were close friends. At the court she also nursed a growing rivalry with Murasaki Shikibu, who had a similar poetic style, though this rivalry pales in comparison with Murasaki Shikibu's spirited competition with Sei Sh?nagon. Izumi Shikibu's emotional poetry won her the praise of many at the court, including Fujiwara no Kinto.

While at the court, she married Fujiwara no Yasumasa, a military commander under Michinaga famous for his bravery, and left the court to accompany him to his charge in Tango Province. She is said to have lived long, outliving her daughter Koshikibu no Naishi, but the year of her death is unknown. The last Imperial correspondence from her was in 1033.

In contemporary arts, the National Opera of Paris and the Grand Theater of Geneva jointly commissioned an opera based on her poems. Titled “Da Gelo a Gelo” by Salvatore Sciarrino and sung in Italian, the work draws on 65 poems from Izumi Shikibu Nikki that features her passion for Prince Atsumichi. It was performed in early 2008 by the Grand Theater of Geneva with the Chamber Orchestra of Geneva.

Shikibu's love poems are full of startling imagery.

(A man willing to smooth the unkempt long hair of a Heian noblewoman must have been very affectionate indeed.)

A large number of Shikibu's poems are . A few examples, first to Tametaka:

Upon seeing her daughter Koshikibu no Naishi's name on her Imperial robes she received after her death: