Kinstones are items from The Legend of Zelda: The Minish Cap. They are special artifacts made by the Minish, which Link can find throughout his quest. Kinstone pieces are halves of a complete medallion. In order to successfully complete a Kinstone, two pieces of the same color and with complementary notches must be used. Once fused, a Kinstone disappears and something special is unlocked. Throughout the overworld, many characters are willing to fuse Kinstones. These characters can be identified by thought bubbles which appear above their heads when Link approaches them.

After completing the first dungeon, Link is given a Kinstone Bag by the Hurdy-Gurdy Man, which allows him to collect and store Kinstone pieces. The most common variety of Kinstone piece is green, and they can be found in non-discreet places such as in grass patches, under rocks, and even as spoils from enemies. Blue pieces are slightly rarer and are more likely to appear in chests, but they can also be found in pots and can be dropped by defeated enemies. Link can use White Picolyte to briefly increase the amount of green and blue Kinstones Link finds when cutting grass or breaking pots. The last normal kind of Kinstone pieces are red, which is considerably harder to find and is almost exclusively found in chests or given to Link by other characters. There are also special gold Kinstone pieces that are usually used to make fusions with inanimate objects to open a pathway. These gold fusions and the one with the Hurdy-Gurdy Man are the only required fusions; the others are completely optional and are not needed for Link to complete his quest. After fusing all of the Kinstones, Tingle turns Link's Kinstone Bag into the Tingle Trophy.

Link can also obtain Kinstones by buying Brioches, Croissants, a Slice of Pie or a Slice of Cake from the Bakery of Wheaton and Pita, by staying in the Happy Hearth Inn or by buying them from the Goron Merchant in Hyrule Town. They are also a random prize for clearing Simon's Simulations.

The symbol in the thought bubble of a willing fuser indicates what sort of special event the fusion will cause. The fusing of a Green Kinstone usually reveals a chest or a secret passageway in a different area. The fusing of red and blue Kinstones often produce unique results, such as making beanstalks grow, aiding in getting a Piece of Heart, or inspiring characters to perform a certain task or to sell a certain item. The fusion of golden Kinstones will in some way open a new path. All of the golden Kinstones must be fused in order for Link to complete his quest.

In the beta stage of The Minish Cap, Kinstone pieces were broken in half horizontally as opposed to vertically, and the Kinstone fusion screen appeared differently. It also seems that the Hyrule Town Shop was meant to sell Red, Green, and Blue Top and Bottom Pieces, suggesting that, as opposed to the final game, where only the left side of a Kinstone piece can be obtained, Link could purchase both the bottom and top halves of a Kinstone.