This chapter investigates the mechanosensing capabilities of B cells and their impact on immune responses. It emphasizes the role of substrate stiffness in regulating B cell activation, highlighting the influence of antigen-presenting substrate stiffness on B cell receptor (BCR) microcluster formation and immunological synapse establishment. The chapter explores how different BCR isotypes exhibit distinct mechanical force thresholds, with IgG-BCRs showing a lower force requirement for activation. It also delves into the mechanosensing roles of motor proteins and the cytoskeleton, and the impact of adhesion proteins like integrins on B cell mechanotransduction. The implications of mechanosensing in autoimmune diseases are discussed, suggesting that B cell responses to tissue stiffness changes may contribute to autoimmunity. This chapter provides a comprehensive overview of B cell mechanosensing, offering insights into how B cells interpret mechanical cues to modulate immune responses and the potential therapeutic implications for autoimmune conditions.