Condiments are rarely consumed on their own. Although addition of condiments to carrier foods is known to affect oral processing behavior and sensory perception, an understanding of how different condiment properties impact oral processing behavior and sensory perception of solid carrier foods is lacking. This study aimed to understand the role of condiments varying in composition and/or rheological properties in bolus formation facilitation, and how they influence oral processing behavior and sensory perception of solid carrier foods. Two carriers (bread, cooked potato) were combined with mayonnaises differing in fat content and viscosity. Addition of mayonnaises changed bolus properties of solid carrier foods considerably (i.e. decreased bread firmness, increased potato cohesiveness, increased lubrication of both bread and potato bolus) and, consequently, facilitated faster bolus formation. While addition of mayonnaises to bread and potatoes decreased the number of chewing cycles before swallowing, consumers did not change muscle activities or jaw movements per chew. No effect of mayonnaise fat content on oral processing behavior of composite foods was observed. Low viscosity mayonnaise resulted in faster bolus formation and swallowing compared to high viscosity mayonnaise. Low viscosity mayonnaise penetrated faster into bread boli leading to faster softening of bread boli. Also in the case of potato, low viscosity mayonnaise lead to faster bolus formation than for high viscosity mayonnaise. The low viscosity mayonnaise mixed more easily with potato bolus pieces, enhancing adhesion between pieces. Both mayonnaise fat content and viscosity influenced sensory perception of composite foods considerably, especially in terms of fattiness and creaminess. We conclude that oral processing behavior, bolus formation and sensory perception of solid carrier foods can be modified considerably by condiments. While composition and rheological properties of condiments have a large effect on bolus formation and sensory perception of solid carrier foods, these aspects have a limited effect on oral processing behavior of composite foods. Oral processing behavior is dominated by the properties of the solid carrier food. Tailoring condiment-carrier combinations could be an effective strategy to increase healthy eating, alter food intake for populations such as the elderly, and increase food appreciation.