Hollywood is collectively saying "howdy" to cowboy hats ... hopping on a trend that's being fueled by Beyoncé's transition to country music.

With Queen B playing some poker on the charts, celebs lately are going full country ... and busting out their Western wear ... particularly above the shoulders. Kim Kardashian, Pharrell Williams, Diplo and Bella Hadid are among the stars being lassoed in to this latest look.

Of course, the poster child for the cowboy hat resurgence is Beyoncé. She's been rocking these 10-gallon hats a lot in recent months ... and we gotta say, she wears them well.

Bey incorporated the look into her "Renaissance" tour, but it's really catching fire now that she's galloping into country with two new songs ... "Texas Hold 'Em" and "16 Carriages."

Some celebs are really going all in, like "Selling Sunset" stars Emma Hernan, Chelsea Lazkani and Chrishell Stause ... pairing their cowboy hats with cowboy boots and chaps, plus a riding bull to boot!!! Safe to say, the cowboy/cowgirl look is all the rage.