He begins a two-year term in January.
Nunnelee, of Tupelo, first won the seat November 2010. The 54-year-old is a former state senator.
His Democratic challenger this year was Brad Morris of Oxford, a 37-year-old attorney and businessman. Morris used to be chief of staff for Travis Childers, the Democratic congressman Nunnelee unseated two years ago.
Also running in the 1st District this year were Libertarian Danny Bedwell of Columbus, the Constitution Party's Jimmie Ray Bourland of Columbus and the Reform Party's Chris Potts.
The district stretches across the Tennessee state line and includes Southaven, Oxford, Tupelo, Columbus and Louisville. It has all of 21 counties and part of Oktibbeha County.