The Naze Millionaires needed a draw to grab the promotion ticket but rallied from a goal down to win the tie.
Kalu Chukwuemeka opened scoring for Sporting on 15 minutes.
Heartland scored twice to win the keenly contested encounter.
YOU CAN ALSO READ: Transfer Updates: United Sign England Mount
The Owerri club joined Sporting Lagos, Kano Pillars and Katsina United in gaining promotion to the NPL.
They will face Northern Conference winners Kano Pillars in the final of the Nigeria National League Super Eight playoffs on Friday.
The four promoted sides will replace the quartet of El-kanemi Warriors of Maiduguri, Nasarawa United of Lafia, Wikki Tourists of Bauchi and Dakkada FC of Uyo, who were relegated from the NPFL at the end of the 2022/23 abridged season.
Written by: Debby Eselebor
3:00 pm - 8:00 pm
Unwind and Energize: Join us on an Electrifying Journey as Kapital FM 92.9 Abuja Presents the After-Work Extravaganza! Tune in from 3PM to 9PM and Let the Vibrant Rhythms Ignite Your Spirit. Welcome to the twilight hours...close