|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|
- February 12 - Franklin D. Richards called and ordained an apostle by Brigham Young
- February 12 - Erastus Snow called and ordained an apostle by Brigham Young
- February 12 - Charles C. Rich called and ordained an apostle by Brigham Young
- February 12 - Lorenzo Snow called and ordained an apostle by Brigham Young
- March 5 - The provisional State of Deseret established and appeals made to the US Government to allow self-rule in the territory.
- October - Brigham Young instructed three of his Twelve Apostles to travel to continental Europe to organize proselyting missions in Scandinavia, France, and Italy.
- December 9 - The first Sunday School established in Salt Lake City.
- February 5 - Charles Wilson Nibley, born to James Nibley and Jane Wilson. He later served as Presiding Bishop of the Church and as second councilor to President Heber J Grant.