Navigating tortuous and delicate vasculature remains a significant challenge in endovascular interventions. This study introduces a novel class of adaptive rigidity sheaths designed to dynamically adjust their stiffness in response to procedural demands, thereby enhancing both maneuverability and safety. Utilizing advanced smart materials and embedded actuation systems, the sheaths can transition between flexible and rigid states based on surgeon input or automated feedback. Computational simulations and benchtop vascular models demonstrate that these sheaths improve catheter steerability, reduce vessel wall trauma, and maintain lumen patency even in high-curvature pathways. Initial in vivo assessments further validate their performance in minimizing procedural complications and improving access to difficult-to-reach vascular targets. These findings suggest that adaptive rigidity sheaths could significantly improve outcomes in complex endovascular procedures, particularly in neurovascular and peripheral interventions.