Gardner, a Democrat from Batesville, died in February. He had been a member of the Mississippi House since 2007. He represented District 11, which includes parts of Panola and Tate counties.
If no candidate receives a majority of votes cast in the special election, a runoff election will be held April 16.
The candidates are Marshall Bartlett, Anderson Boothe, Michael Cathey, Lataisha M. Jackson and Ederic L. Kerney.