The CCC-Liv rider clocked a time of 28 minutes and 24 seconds on the 20km route. Moolman Pasio was nearly a minute faster than runner-up Carla Oberholzer.
Frances Janse van Rensburg placed third and was the first U23 rider to finish.
“The plan was to get started quickly because the road got slightly uphill,” said Moolman Pasio.
“Quite soon I had Carla Oberholzer in sight; she was a target point for me.
“After the turning point I passed her. Then I noticed that I had given quite a lot under these warm conditions. I continued to drive full throttle and am very happy with this success,” said Moolman Pasio.
On Saturday Moolman Pasio will be defending her title in the road race.