Dealing with online business is a very challenging job for an enterprise. Online demands are very unpredictable in practical situation, and fulfilling the demand on time is another typical job to handle. In this study, an inventory model has been developed for online B to C (Business to Customer) business with just in time (JIT) deliveries. Kanban system is also being considered which is a critical part of JIT implementation which helps in managing proper work flow in an organization. A mathematical model has been developed in this study considering a single enterpriser with online B to C business. In the present model, Kanban cost is also introduced which increased the efficiency of model. The Kanban system maintains the flow of the inventory, and with the help of the visible cards information is shared which shows what work is in progress, what is required and what task have been done. It raises the level of sustainability, and there is no chance of excess inventory. A single product has been considered with JIT implementation which is one the sustainable approach. Demand is considered to be exponential with no shortages. Carbon emission cost is considered in the model. A model is analyzed, and an optimum solution has been found out in the numerical section through Mathematica 12 software. Numerical exemplification and lemma are carried out to validate the model. Different and influential parameters have been validated with the help of the Sensitivity Analysis technique. Pictorial depiction has been examined with respect to influential parameters of the model through Origin 2019.