World number one Halep came through a tough three-set semi-final against Maria Sharapova on Saturday and was well off the pace, failing to coax even a single break point opportunity the entire match.
"It's amazing that I could come and defend my title here. It's really something very special for me," Svitolina said after defeating Halep in the Rome final for the second year in succession.
The Ukrainian, who has now won the last eight finals she has appeared in, stormed out of the blocks and kept Halep under relentless pressure, serving at a high level and chasing down everything the Romanian sent her way.
Halep converted only 15 percent of her first serves into points in a dire first set, and though she improved that ratio in the second, she made a total of 21 unforced errors to end any hopes of a comeback.
Svitolina wrapped up the victory in 67 minutes on her second match point, leaping into the air in celebration as Halep tamely netted a backhand.
On current form the Ukrainian will be surely ranked among the favourites to triumph at the French Open. The Roland Garros showpiece begins on May 27, and Svitolina insisted that she would not get ahead of herself.
"I will try to take one match at a time, it's very important in a grand slam," she added. "It's very tricky so we'll see how it goes, but definitely I'm going to enjoy (going to) Roland Garros on a high note."