Blind singer Fanny Crosby authored the words of this hymn after listening to a melody composed by Phoebe Knapp in 1873. It is based on Hebrews 10:22” Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.” (KJV)

The hymn appeared in the July 1873 issue of Palmer's Guide to Holiness and Revival Miscellany, a magazine printed by Dr. and Mrs. W. C. Palmer of 14 Bible House, New York City. The popular song reflects Crosby's walk of faith, as expressed in Philippians 1:21, "For to me, to live is Christ and to die is gain" (ESV).

"Blessed Assurance" (1873) is one of the ten most popular hymns sung by United Methodists according to Carlton Young, and it is one of eight Crosby hymns in The United Methodist Hymnal. "Blessed Assurance" was published in 1873 in the monthly magazine edited by Joseph Fairchild Knapp and Phoebe Palmer Knapp, Guide to Holiness.