|Centuries:||18th century - 19th century - 20th century|
|Decades:||1810s 1820s 1830s - 1840s - 1850s 1860s 1870s|
|Years:||1840 1841 1842 1843 1844 1845 1846 1847 1848 1849|
- January 29 - Joseph Smith nominated as a candidate for President of the United States by a political convention in Nauvoo.
- Joseph Smith confers on the Quorum of the Twelve Apostles all of the ordinances, keys, and authority that he possesses
- Last meetings for the Female Relief Society held in Nauvoo.
- April 7 - The King Follett Sermon is delivered by Joseph Smith
- April 30 - Addison Pratt starts mission in Tubuai, the first missionary in the South Pacific.
- June 7 - William Law publishes the first and only edition of the Nauvoo Expositor.
- June 10 - Nauvoo city council ordered destruction of Nauvoo Expositor
- June 11 - Joseph Smith and the Nauvoo city council charged with riot in the destruction of the Nauvoo Expositor press.
- June 18 - Nauvoo is placed under martial law by Joseph Smith
- June 22 - Joseph Smith and Hyrum Smith surrender themselves to Governor Thomas Ford to answer charges laid against them.
- June 27 - At Nauvoo, Illinois, Elder John Taylor writes a eulogy announcing the martyrdom of Joseph Smith which is later cannonized as D&C 135.
- June 28 - The bodies of Joseph Smith and Hyrum Smith are placed into two separate wagons and taken to Nauvoo by Willard Richards, Samuel Smith and Artois Hamilton.
- August 8 - Sidney Rigdon's request to be appointed guardian of the Church was rejected by a special conference, and Brigham Young was sustained in his assertion that leadership should fall to the Quorum of the Twelve Apostles.