Goals from Raymond Monama and Mongezi Bobe handed Lidoda Duvha a deserved victory, after the first leg between the teams on Wednesday evening had ended goalless.
Leopards last played in the top flight in the 2007/08 season.
The pitch at the Tshifulanani Stadium was hardly fit for a match of this magnitude and importance, proving to be simply too bumpy and uneven for either team to string passing moves together.
Nonetheless, Leopards started brightly and took the lead in the 10th minute. A Mongezi Bobe cross from the left was picked up by Raymond Monama, who cut inside onto his left foot and fired home a low drive to put Leopards in the driving seat.
The Limpopo team came within inches of doubling their advantage on 15 minutes, as striker Rodney Ramagalela twice hit the crossbar from almost identical headed efforts that were separated by seconds.
Bay United gradually gained a foothold in the match and looked dangerous whenever they managed to play crosses into the box, with Ivorian striker Bryce Aka always looking likely to beat the Leopards central defenders in an aerial battle.
In the 37th minute Aka almost brought Umlilo level, getting an acrobatic volley on target only to see Leopards goalkeeper Azwindini Maphaha tip the ball over the crossbar.
Leopards continued to look the likelier scorers in the second half, and the skilful Khetho Masuku almost scored with a stunning long-range strike that was well saved by Modiri Marumo, before centre-back Mashlane Phadu made a desperate goal-line clearance.
But the hosts were not to be denied a second goal, and captain Bobe provided it in the 56th minute, scoring with a powerful header after left-back Edward Tshabalala had floated in a hopeful cross that was poorly defended by Bay.
Leopards saw out the rest of the match in relative comfort, with their only worry coming just after the hour mark when Maphaha succumbed to a back injury and made way for Thabang Maluleke.
The replacement keeper looked nervous at first but settled well after getting a few touches of the ball.
Black Leopards (1) 2 (Monama 10 Bobe 56) Bay United 0
Leopards: (4-4-2) Maphaha (Maluleke 63rd); Vezi, Mabusela, Nyirenda, Tshabalala; Bobe, Ng’ambi, Monama (Manaka 85th), Masuku; Masanabo (Metsi 60th), Ramagalela
Bay: (4-4-2) Marumo; Mkhabela, Phadu, Sithole, Gallagher; Mothapo (Sikhwivhilu 46th), Galane, Ngalo, Machaka (Yekise 59th); Nontshinga (Zondi 69th), Aka
Referee: Daniel Bennett Cautions: Mothapo BackpageTxt