This is a list of units from Mississippi that served in the Union during the American Civil War. Only a single unit of white Union troops was raised within the state, along with several regiments of African-American volunteers, eventually becoming part of the United States Colored Troops. The list of Confederate Mississippi units is shown separately.

Units

• 1st Battalion, Mississippi Mounted Rifles (Union)
• 1st Mississippi Cavalry Regiment (African Descent) – redesignated 3rd U.S. Colored Cavalry Regiment
• 1st Mississippi Heavy Artillery Regiment (African Descent) – redesignated 5th U.S. Colored Heavy Artillery Regiment
• 2nd Mississippi Heavy Artillery Regiment (African Descent) – redesignated 6th U.S. Colored Heavy Artillery Regiment
• 1st Mississippi Infantry Regiment (African Descent) – redesignated 51st U.S. Colored Infantry Regiment
• 2nd Mississippi Infantry Regiment (African Descent) – redesignated 52nd U.S. Colored Infantry Regiment
• 3rd Mississippi Infantry Regiment (African Descent) – redesignated 53rd U.S. Colored Infantry Regiment
• 4th Mississippi Infantry Regiment (African Descent) – redesignated 66th U.S. Colored Infantry Regiment
• 5th Mississippi Infantry Regiment (African Descent) – organization not completed
• 6th Mississippi Infantry Regiment (African Descent) – redesignated 58th U.S. Colored Infantry Regiment