Jorgensen finished in one hour 55m 36s, ahead of Britain's Non Stanford and Vicky Holland who were 29s and 44s back respectively.
The American has won her last 12 elite races.
Hewitt raced eight International Triathlon Union elite events this season. She secured two podium finishes but always finished inside the top eight. She didn't finish the Olympic test event in Rio.
"On the swim I was a little bit further back than I wanted but got into the main group on the bike.
"We went tightly around the corners to keep about a 40s gap to the second group right down to the run. I didn't know where Katie [Zaferes] was at the back of the bike [leg] but I managed to come out on top.
"I went out conservatively on the run, then pushed to go out by myself for the majority."
Of the other New Zealanders in the grand final, Simone Ackermann finished 26th, Rebecca Spence 43rd and Rebecca Clarke 45th.
The men's elite race is tomorrow, featuring New Zealander Ryan Sissons.