The 'Approved Supplier Lists' functionality in Oracle Fusion Cloud Sourcing serves multiple purposes. It allows organizations to maintain a list of trusted suppliers for procurement activities, ensuring that only approved suppliers are considered for sourcing requests. It also helps in enforcing compliance with corporate procurement policies by allowing the establishment of preferred supplier relationships and restricting purchases to approved vendors. Additionally, it streamlines the supplier onboarding and qualification processes by providing a centralized repository of supplier information and performance metrics.