The second seed from Slovakia needed 95 minutes to overcome her fatigued French opponent, whose sixth double fault of the contest gave Cibulkova three match points.
Cibulkova needed only one, falling on her back in joy after converting it.
"Today I played well all through the match," said Cibulkova, who added the title to the trophy she won in Moscow last year. "In the past finals I was nervous. This was the first one where I just went for it - everything went my way.
"I've changed my coach recently, and I'm more relaxed on the court. It's all working out really well for me," added the 23-year-old, who will represent Slovakia at the London Games in both singles and doubles.
Bartoli ran out of steam after a long week on court that included a series of three-set matches as she struggled with a sore hip.
By the time they reached the final, world No 10 Bartoli had spent a total of four more hours on court than Cibulkova.
Cibulkova, who is slated to rise one place to 13th in the world when the rankings are released on Monday, was playing in her second final of the season, after losing in the title match in Barcelona.
The Slovak broke Bartoli three times in the first set, Bartoli making it easier with a double fault on set point.
Bartoli turned the tables with two service breaks for a 4-1 lead in the second, but the Slovak responded by winning four straight games.
"I fought for every ball and didn't give up on the important points," she said. "I really fought for it. My tactic was to move her around, make her move and go for my returns."
Cibulkova broke Bartoli for a second time in the set to knot the score at 4-4, winning 13 of 16 points during that surge.
Cibulkova then broke Bartoli one last time to seal the match in which she won six of the last seven games.
"I lost, but Dominika played a great match," said Bartoli, who won't be playing at the Olympics due to a long-running dispute with French tennis officials over the continuing presence of her father, Walter, as her only coach.
"I wish her good luck at the Olympics," Bartoli said. "I fought hard in my previous matches, today I just came up a bit short."
Bartoli was playing her first day match after winning three tough ones at night and said the change made a difference to her game.
"Dominika played all her matches during the day, she was maybe more used to it, especially in that first set.
"I played well to get the lead in the second, but from this point I started to feel a bit tired and not moving so quickly as I wanted. But she played very fast and extremely well, so she made me feel uncomfortable.
"I always want to win, so obviously I'm disappointed because I was not able to do it.
"I really wanted to head back to Europe with a good week, a good strong week that I would be able to build on before Canada and Cincinnati," added Bartoli, who will return to the hard courts of North America at those venues in August.