Advancements in the footwear industry have led to new innovations in comfort and performance. For example, new insoles are designed to increase comfort and reduce peak ground reaction forces. The introduction of carbon fiber plated running shoes has also led to multiple record-breaking performances. However, advantages of shoes with multiple plates on injury risk and performance are unknown. Therefore, the purpose of this study was to analyze the effects of a novel orthotic insole (Kingetics, LLC, USA) consisting of two rigid plates on walking and running biomechanics. The effects of the dual-plate insoles were compared with an on-market carbon fiber running shoe and a shoe with no plates or cushioning. Ten healthy male participants performed ten treadmill trials with five shoe conditions (no insoles or cushioning, insoles with three increasing stiffness levels and a carbon fiber running shoe) at both their self-selected walking and running speeds. Peak ground reaction force (GRF), ankle moment, positive ankle power and metatarsalphalangeal (MTP) joint angle were compared between the insoles and the carbon fiber shoe. Participants also rated the comfort of each shoe. The stiffest Kingetics dual-plate insoles were more effective than the carbon-plated shoe in reducing peak vertical GRFs during walking and posterior GRFs during walking and running. The insoles increased the ankle moment whereas the carbon fiber shoe decreased the ankle moment. However, both conditions decreased ankle power relative to a shoe without insoles or cushioning. There were no significant differences in MTP joint angle between any conditions. Overall, participants rated the carbon fiber shoe as more comfortable than the dual-plate insoles. These results highlight the effects of insoles with multiple rigid plates and how they compare to an on-market carbon fiber shoe and a shoe without insoles or cushioning, which can help inform the design of footwear aimed at reducing peak GRFs and ankle loading.