The victory placed Wozniacki top of the red group, with the emphatic nature of her victories meaning she could not be caught by two players, prior to the later match between Svitolina and France's Caroline Garcia.
On Friday, Svitolina faces Halep and Garcia takes on Wozniacki to determine who will advance from the Red Group.
The world number eight was down a set and a break to Elina Svitolina in the second round-robin match of her tournament debut and suddenly burst into tears as she walked back on court following a pep-talk from her coach and father Louis-Paul. Wozniacki looked in great form, and she was able to consistently find her first serves as she easily consolidated the break for an early 3-0 lead after just a mere 15 minutes of play.
Also, Caroline Wozniacki of Denmark, the 2010 runner-up, never surrendered in beating Elina Svitolina of Ukraine 6-2, 6-0 for the first time in four matchups.
With the victory at the Singapore Indoor Stadium, Wozniacki has recorded three wins against world No. 1 players in 2017, having defeated Garbine Muguruza en route to winning the Pacific Open in Tokyo and Karolina Pliskova at the Rogers Cup in Toronto.More news: Trump has no plan to block scheduled release of JFK records
The second was more competitive but Halep struggled to contain both the brilliance of her opponent and her own negativity and succumbed rather meekly.
"The court is a little bit slow and I felt a little bit heavier on court", she said.
"I think playing the top players in the world means you have to play your best level to beat anyone here", the 27-year-old added. "I felt comfortable, played aggressive when I needed to and ran the balls down when I needed to. Also I did some good shots, good points, and I missed too many to win a match".
Svitolina and Garcia's match lasted more than twice as long as the one that preceded it and was the second dramatic encounter between the pair this month. I think if I just could keep the ball in, I could have been much better.
However, Halep quickly grew in confidence and she gained a decisive break in the ninth game of the match, thanks in part to two costly double faults from the French player, and secured the opening set with a precise backhand victor. "It was very hard, a lot of emotion, some up and down, but at the end I could control myself better than she did".