Wozniacki, who had won the last three meetings between the two, moved into a 4-1 first-set lead, before Halep pegged the Dane back to a tie-break. The world number two recovered, however, taking four set points along with a match lead.
Halep's gruelling run to the final began to show in the second set, as the Romanian forced a timeout for dizziness. The top seed battled on following the break, and levelled the match with a 6-3 win.
Wozniacki responded early on in the deciding set, securing a 3-1 lead, before Halep stormed to victory in four of the next five games to take make it 5-4.
Halep, who had shown signs of fatigue in the second set following her timeout, eventually cracked as Wozniacki secured the next two games and a first Grand Slam title in the process.