By 1827 Whitney had entered into a partnership with Algernon Sidney Gilbert to run a store in Kirtland known as N.K. Whitney & Co. It would later become Mormonism's first "bishop's storehouse." The building was also used by Church founder and presidentJoseph Smith as a home and office. Joseph received 16 revelations (D&C 84 through D&C 98 and D&C 101) in the Whitney Store and used one of the rooms as a meeting place for the School of the Prophets, a place where many spiritual manifestations were received.
While in Nauvoo, Illinois, Whitney was involved in some important developments within the Church. One of these occurred on May 4, 1842 when Whitney, along with a group of nine others, met in the upper story of the Red Brick Store. Those who were there, including Whitney, became part of Joseph Smith's Quorum of the Anointed. Later, Whitney's wife, Elizabeth Ann, was added to that group.
Another development was polygamy. In 1842, after being taught the doctrine of polygamy, Whitney and his wife agreed to let their daughter, Sarah Ann, become a plural wife of Joseph Smith.