Sarah was born on January 10, 1804 in West Nantmeal Township, Chester County, Pennsylvania, and died at Salt Lake City, Utah on March 20, 1858. She was the daughter of Elijah Malin, Sr. and Catherine Essick, and the granddaughter of Thomas Malin, Jr. and Hannah Griffith.

Sarah Malin (often misspelled as Mellon, etc.) was married in polygamy to Brigham Young on April 18, 1848. She was Brigham's 44th wife (he married or was sealed to an estimated 54 women following the marriage to his first wife). The marriage was said to have occurred in a cave at Winter Quarters or Far West, along the Missouri River near present-day Omaha, Nebraska, while the Malin family was traveling from Nauvoo, Illinois to Salt Lake with the Ezra Taft Benson Company. It is recorded that Sarah and Brigham later divorced.

In the winter of 1838, the Prophet Joseph Smith visited Chester County and most of Elijah's family accepted the message he brought. Elijah Malin, Jr., Sarah's brother, was president of the Chester County Branch of the Church of Jesus Christ of Latter Day Saints, a position he held until moving to Nauvoo, Illinois around 1845. It was at Nauvoo, on December 18, 1845, that Elijah, Sr. and Catherine Malin received their endowments. They also had received patriarchal blessings from Hyrum Smith (older brother of Joseph Smith, Jr., an LDS founder) on March 17, 1844 while living in Nauvoo.

Through a series of letters, published in the New York Times during January and February, 1855, Sarah had set out, along with Eliza Williams, to give lectures about what they believed to be the evils of Mormonism. Her first lectures were to be given in Boston, Massachusetts. There is no further information whether she actually did give such lectures or what the consequences of doing so might have been.