Between the ages of 12 and 15, Smith briefly attended Moor's Charity School on the campus of Dartmouth College while his family lived in nearby Lebanon, New Hampshire.

[2] Smith was a close advisor and confidant to his brother Joseph as the latter produced the Book of Mormon and established the Church of Christ.

[4] When the Church of Christ was organized on April 6, 1830, six men signed their names as charter members; at the age of 30, Hyrum Smith was the oldest of the six.

Smith served as presiding officer of a church branch in Colesville, New York, and was one of the first Latter Day Saint missionaries in the surrounding area.

In 1834, under the direction of Joseph Smith, he recruited members for a militia, Zion's Camp, and traveled with the group to the aid of the Latter Day Saints in Missouri.

In 1838 and 1839, Hyrum, Joseph and three other church leaders shared a jail cell in Liberty, Missouri, while awaiting trial.

Although Hyrum Smith was never explicitly ordained to the priesthood office of apostle, "his appointment as assistant president may have included such authority".

While attempting to barricade the door to prevent the mob from entering, Hyrum was shot in the face on the left side of the nose.

M. Russell Ballard, who was the Acting President of the Quorum of the Twelve Apostles of the LDS Church, was also a direct descendant of Smith.