Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.

In a mixing bowl, whisk together flour, baking powder, salt, and sugar.

Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs.

Stir in the buttermilk until just combined, then gently fold in the blueberries.

Turn the dough onto a floured surface and pat it into a rectangle about 1-inch thick.

Cut the biscuits out using a round cutter and place them on the baking sheet.

Bake for 15-20 minutes until the tops are golden.

Remove from the oven and let cool for 5 minutes before serving.