“It is alleged that he was going to deliver it to a certain location and we pounced on him,” said Hawks spokesman Paul Ramaloko.
“We found 40kg, and each kilogram goes for about R1.2 million.”
Ramaloko said the drugs were brought into the country, but he could not disclose where it was coming from as it would compromise their investigation.
The man was believed to be part of an international drug distribution network.
Police said more arrests were imminent.
Two unlicensed firearms were also found in the house.
The man is due to appear in the Johannesburg Magistrate’s Court on Tuesday on a charge of dealing in drugs.