In their first encounter in Durban on 27 February last year Bopape (10-8; 9) won on a split ten-round points decision in a non-title fight.
Mhlongo (23-9-1; 18) had previously won the vacant South African junior middleweight title and made five successful defences to win the championship belt outright, one of the few fighters to achieve this in recent years.
He won the title on 6 August 2011 with an eighth-round technical knockout win against Page Tshesane, and has also held the World Boxing Association’s African title and the World Boxing Federation’s Intercontinental junior middleweight title.
The fight will be top of the bill at the venue named after the late Petrus Malemela, who was the owner of the Bloemfontein Celtic football club.
On the undercard the No 5 rated Mpho Seforo (8-2-1; 3) goes in against the No 7 rated Zolile Miya (8-7-1; 6 )in a scheduled six-round flyweight bout.
There is also a woman’s bout on the card at junior lightweight, between South Africa’s Matshidiso “Scorpion Queen” Mokebisi against Cicilia Pitiseni of Zimbabwe