The DA has defeated the ANC in Beaufort West for the first time, according to provisional results.
The provisional results show the DA with 49.2% of the vote, followed by the ANC at 42.2%.
The Karoo Democratic Force received 4.05% and the EFF 1.39%.
Western Cape Premier Helen Zille said that winning Beaufort West, which was regarded as an ANC stronghold under controversial Mayor Truman Prince, was not a complete surprise.
"I went to Beaufort West during the election, and I came back thinking that we would win it.
"It is the first time that we have won Beaufort West, but I had a sense that it was coming," said Zille.
Beaufort West is also Cape Town Mayor Patricia De Lille's hometown.