Transport is the backbone of the economy aiming to move people and goods efficiently. The gross domestic product is collected from vehicle taxes, energy taxes, and taxes on fuel. On the other side, 25% of the CO₂ emission of the whole transport sector comes from urban transport. Simultaneously, new technologies are developed and applied in real life, and E-commerce represents approximately 10% of the global retail landscape. Although home delivery is convenient for the customer, last mile delivery (LMD) poses significant logistical challenges for companies. The aim of this paper is to propose an approach to cost-optimal routing of a truck-and-drone system for LMD. The applied solution is an algorithm based on a combination of the combinatorial optimisation genetic algorithm. The experimental results demonstrate that it is possible to optimise last mail delivery and significantly reduce total distance for truck route and drone route.