Key Performance Indicators (KPIs) in last-mile delivery measure the efficiency and effectiveness of the delivery process. Some essential KPIs include delivery time accuracy, tracking the on-time delivery rate, measuring customer satisfaction through feedback, monitoring the rate of successful first-time deliveries, calculating the cost per delivery, and analyzing the utilization and efficiency of delivery vehicles and drivers. These KPIs help businesses evaluate their last-mile performance and make necessary improvements, ensuring timely and satisfactory delivery experiences for their customers.