The former Wimbledon finalist handled the difficult conditions much better than the Australian on the English south coast, winning 6-3, 6-1.
In wild winds, Stosur struggled to find any rhythm in her game and eventually succumbed in 70 minutes on centre court.
Her normally lethal serve was off in the gusty conditions, winning just 56 per cent of points on her first serve.
Bartoli then later went on to defeat Petra Kvitova 6-1, 4-6, 7-5 in the final to claim the first grasscourt title of her career.
Kvitova had progressed after Daniela Hantuchova retired at 7-6 (9-7), 4-2 down.
It was world number 10 Stosur's third semi-final appearance at Devonshire Park, and she had shown encouraging signs before Wimbledon in her opening three rounds, defeating world number three Vera Zvonareva on Thursday.
The Queenslander's attention will turn fully to Wimbledon, where she will meet unheralded Hungarian Melinda Czink in the opening round.
Stosur has never progressed beyond the third round in eight visits at the famed grand slam tournament.
"It's been a really good week for me in spite of this match," Stosur said.
"I'm going into Wimbledon feeling quite good.
"I think I played some really good tennis here and got through some really good matches.
"It's been pretty much been exactly what I would want going into Wimbledon.
"I thought the other day when I played Vera it was the worst [conditions] I'd ever played in, but I think today was even worse than that.
"It definitely wasn't easy at all. It's one of those days where you've just got to try hard and do whatever you can to get through because it's very hard to try and hit the shots that you want."
-AAPTags: sport, tennis, australia, united-kingdom, england First posted June 18, 2011 23:00:00