The role of functional mobility and its relationship with injurious falls among lower limb prosthesis users has conflicting evidence, potentially confounded by several studies assessing falls early in the rehabilitation process or not differentiating between an injurious and non-injurious fall. The purpose of this study was to estimate the association of functional mobility and injurious falls among adults who utilize a lower limb prosthesis. A sample of 12,044 adults with unilateral amputation were analyzed with a median time since amputation of five years. Two different analytic approaches were applied, the first utilized quartiles as defined by the PLUS-M and the second utilized clinically relevant levels, which included characteristics such as amputation level, age and functional classification, mapped to the PLUS-M scores. Lower functional mobility was associated with an increased risk of injurious falls, which are associated with healthcare utilization (e.g., doctor visits or emergency department use) and thus more of an economic burden. These findings indicate the importance of focusing on an individual's functional health, mobility, and independence.