The dismissal with costs upheld the approval decision made in November.
Sibanye-Stillwater and Lonmin said they both remained fully committed to the offer, which the former upped last month
Sibanye-Stillwater CEO Neal Froneman was pleased with the decision.
"We are confident that the integration of Lonmin's PGM assets and Sibanye-Stillwater's adjacent PGM operations will ensure a more sustainable and positive future for these assets ... in the best interest of all stakeholders," he said.
Lonmin CEO Ben Magara also welcomed the decision, which cleared the way for shareholders to vote on the acqusition on May 28.
The UK Competition and Markets Authority unconditionally cleared the proposed acquisition in June.
Sibanye-Stillwater's (JSE:SGL) shares were trading at R11.43 (US80c) per share Friday, 7% higher than at the sart of the year, while Lonmin's (LSE:LMI) shares were at 62.3p, (US79.63c) up 32.2% from January 2.