The province will have the Economic Freedom Fighters (EFF) as its official opposition after the newcomer narrowly beat the Democratic Alliance (DA) for the votes of ANC deserters.
It dropped a full six percentage point in North West, but the ANC comfortably held the province in which the Marikana massacre took place.
North West is the third province in which tallying was completed, after the results fro the Northern Cape and Mpumalanga were released on Thursday night.
In final results published on Friday morning, the ANC received 67.8% of the national vote in North West, leaving it in undisputed control of the provincial legislature.
Second place was not nearly so clear. In what seems likely to be the tightest race for the opposition title in any province, the DA and EFF were separated by only 6 644 votes in the provincial race. But while the DA drew more votes in the national election, the EFF beat it in the provincial race to become the official opposition.
The EFF is also near certain to be the official opposition in Limpopo, with the DA to oppose the ANC in all other provinces except the Western Cape if, as expected, it supplants the Inkatha Freedom Party in KwaZulu-Natal.
In the 2009 elections, the Congress of the People narrowly held second place in the North West provincial election, but it was again humiliated, as in the other two finalised provinces, with only 10 256 provincial votes, or less than 1%.
A combination of Marikana and the agonising strike in the platinum sector confounded initial predictions and projections for both the ANC, which could legitimately have hoped to stay above 70% in the province, and for the DA, which was expected to have closer to a fifth of the total vote