An orthopedic walker boot for wearing on a lower limb of a wearer has a rigid external shell, a pliant internal boot positioned in the external shell, and a heel plate selectively detachable or attachable to the external shell. Selective transition of the heel plate between the detached condition and attached condition selectively provides the orthopedic walker boot with an open-heel configuration or a closed-heel configuration. The external shell includes an outer sole having a walking surface which is configured with two curved axes to facilitate walking while wearing the orthopedic walker boot.