The stability and fat‐replacer properties of mayonnaise prepared with oxidized sweet cassava starch is studied. In a first step, the oxidation of starch using different conditions, i.e., thermal and thermochemical processes with the redox pair system (H2O2/NaHCO3), is analyzed. Oxidized starches can be used to produce food grade emulsions without the addition of surfactant, then, the mayonnaise emulsions are prepared using oxidized starch paste as partial substituent of the fat. They show greater stability with respect to the mayonnaise prepared with the native paste due to electro‐steric effects and Pickering type that the oxidized starch exerts on the emulsion. The rheological performance of mayonnaises with oxidized starches is analyzed and compared with that of full‐fat mayonnaise; demonstrating the oxidized starches applicability as stabilizers and fat‐reducers. Finally, a sensory analysis of the mayonnaise emulsions is carried out where all mayonnaise samples are judged to be sensorially acceptable.