Saints, just relieved to still be in existence after going into administration last term, host the Lions on Saturday, August 8.
They then face trips to Huddersfield and Swindon before League Two champions Brentford visit St Mary's on August 22.
Saints will head to fellow relegated side Charlton on September 5, and host Norwich, the third side to drop out of the Championship, on November 21.
They will travel to Carrow Road on February 20, while the Addicks will make the trip south on April 10.
Exeter provide the opposition at St Mary's on Boxing Day, while Saints will end the season with a home game against Southend.