The 24-year-old from Moscow wrapped up her 6-2, 6-0 victory in 61 minutes to record her first Tier I tournament success, and deny Hingis her fifth crown in Tokyo.
"I felt like I played up to my potential today," Dementieva was quoted as saying by the WTA official website. "I just went for all of my shots and I was serving pretty well also.”
“She's (Hingis) a great champion and I was happy for the opportunity to play her here for my first Tier I title,” said Dementieva, whose world ranking will rise to number eight in the new rankings coming out on Monday.
Hingis, who was bidding for her first singles title since her return from a three-year injury-forced retirement, had to overcome two Russians, Maria Kirilenko and Maria Sharapova, before she fell to Dementieva in the final.
The 25-year-old Swiss, who was competing in her fourth tournament since she officially returned to the game, was unranked till mid last month but her ranking is expected to soar up to 52 in the world on Monday, following her impressive run in Australia last month and in Tokyo this week.
"I am proud of my week, I have surpassed all my expectations of my comeback and feel very good knowing I can go out there and play with the best players in the world,” said the former world number one.
“I really enjoyed my week in Tokyo and look forward to coming back next year and trying to take my fifth title here,” added Hingis.
Dementieva is now 3-2 against Hingis, who prevailed in their first two meetings at the Australian Open and in Moscow but has been undermined by the Russian ever since.