Wow, there are so many styles and types of cowboy hats. Do you want to look like a cowboy, rock a country music singer curl, show your patriotism with an American flag on your hat or show up here-for-the-party? You can do it and all these hat styles are mostly unisex. Sometimes a hat works better for a woman just because it's colorful or the trim (the hatband or other design on the hat) is feminine.
Most of all, a hat needs to be in proportion to the width of your eyes and face, as well as your shoulders.
When the proportion is right men and women can rock the same styles. The Kenny is a perfect example of at hat for girls or guys. Notice how these hats are shaped to follow the width of their faces.
Sometimes attitude alone is enough to make a hat work for a man or woman. These two hats are traditional styles with large brims, but you can see that with confidence they both pull it off. Notice that before the sides curl up, both hats are shaped in front to be in proportion to the width of their eyes and she has shaped her hat so that it isn't wider than her shoulders. He is wearing the Brad and she is rocking the Jason.