Ms Cox, from Corrimal, gained 22.5 per cent of the formal vote on Sunday afternoon, which will see her easily elected in the northern suburbs.
In central Wollongong, Ms Blakey had just under the required 20 per cent of the vote, which will get her across the line.
These results are well up on the 2011 election, when the party got about 13 per cent of the primary vote in wards 1 and 2.
Mx Cox labelled this “an amazing election result”, saying it was the highest primary result for the Greens at any election since 2002, when Michael Organ was elected as the Member for Cunningham.
"Cath and I have both been comfortably elected to council,” she said.
However, alpaca shearer Jamie Dixon – the first council candidate run by the party in the southern suburbs – is unlikely to be elected with 9.8 per cent of the vote.
Ms Cox, who ran as the mayoral candidate, received just over 10 per cent of votes.