It is used as a component of baking powders and baking mixes, as mordant in textile dyeing, as reducer of chromium trioxide in mordants for wool, as a metal processing agent that prevents oxidation, as an intermediate for other potassium tartrates, as a cleaning agent when mixed with a weak acid such as vinegar, and as reference standard pH buffer.

In culinary applications, potassium bitartrate is valued for its role in stabilizing egg whites, which enhances the volume and texture of meringues and soufflés.

Its acidic properties prevent sugar syrups from crystallizing, aiding in the production of smooth confections such as candies and frostings.

Additionally, potassium bitartrate is used to stabilize whipped cream, allowing it to retain its shape for longer periods.

[16] As cream of tartar is added, the pH decreases to around the isoelectric point of the foaming proteins in egg whites.

Foaming properties of egg whites are optimal at this pH due to increased protein-protein interactions.

[16] As an acid, cream of tartar with heat reduces sugar crystallization in invert syrups by helping to break down sucrose into its monomer components - fructose and glucose in equal parts.

[18] Preventing the formation of sugar crystals makes the syrup have a non-grainy texture, shinier and less prone to break and dry.

However, a downside of relying on cream of tartar to thin out crystalline sugar confections (like fudge) is that it can be hard to add the right amount of acid to get the desired consistency.

[18] Upon dissolving in batter or dough, the tartaric acid that is released reacts with baking soda to form carbon dioxide that is used for leavening.

Cream of tartar was often used in traditional dyeing where the complexing action of the tartrate ions was used to adjust the solubility and hydrolysis of mordant salts such as tin chloride and alum.

A commercial retardant premix additive sold by USG to trade interior plasterers includes at least 40% potassium bitartrate.

This process is now obsolete but produced a higher quality (reasonable purity) than "potash" extracted from wood or other plant ashes.