The League Cup will be known as the Capital One Cup from the start of the new season under a four-year sponsorship agreement with the credit card company, the Football League has announced.
Saints will enter at the second round stage of the competition in the upcoming campaign.
The value of the new sponsorship deal was not disclosed.
Football League chief commercial officer Richard Heaselgrave said: "This is terrific news for clubs and a great way to conclude what has been a memorable domestic football season.
"The Capital One Cup is in great shape having been re-invigorated in recent seasons by a number of memorable finals, some thrilling midweek cup football and a first glimpse of the stars of the future."
The draw for the first round of the rebranded competition will be made on June 14, with the final scheduled to take place at Wembley on February 24.