Potassium cobalt(III) nitrite is primarily used in analytical chemistry as a reagent for the qualitative detection of potassium ions. It forms a characteristic yellow precipitate with solutions containing potassium, aiding in identification during qualitative analysis. Additionally, it serves as a precursor in the synthesis of other cobalt compounds, which find applications in catalysis and materials science. Its role in inorganic synthesis and chemical analysis makes it a valuable reagent in laboratory settings.