The fight will be staged by promoter Tshele Kometsi's TK Boxing Promotions at Wembley Arena, Johannesburg.
The star-studded bill includes Tshifhiwa "Atomic Spider" Munyai.
Mthalane's defence against the current national champion from Mdantsane was confirmed in midweek by IBO president Ed Levine.
Kometsi had requested that the IBO championship committee sanction Nxoshe, who has 15 wins, seven losses and a draw.
"This sanction is conditioned upon my receipt of approval from the IBO championships committee to give an exception to Nxoshe to challenge for our world title with his current ranking of 46 in the IBO ratings," Levine wrote in his response to Kometsi.
"This tournament is also sanctioned with the express condition that all sanctioning fees must be received by the IBO no later than 30 days before the tournament."
Mthalane, from Lindelani in KZN, last saw action in December 2015 when he stopped Renz Rosia from the Philippines in the ninth round in Durban.