In the academic literature, there are studies that link the adoption of Industry 4.0 technologies with an improvement in product-related circular economy indicators. However, there are scarce studies carried out in business contexts that analyse the degree, the stage of the life cycle and the value given to these improvements by customers and Industry 4.0 technology manufacturers. To contribute to clarifying these fields, a multiple-case study of nineteen technology manufacturers has been conducted, with input from the experience of venture clients as users and active participants in a shared project. Both manufacturers and their customers agree that Industry 4.0 technologies have a positive impact on circular economy. Benefits depend on the type of technology and its application and are mainly concentrated in the manufacturing phase. Additive manufacturing appears to be the technology with the greatest potential to influence circular economy, but customers also highlight the influence of augmented/virtual reality. Most manufacturers and customers emphasise the biggest influence is on reducing material consumption. This serves to improve the critical variables of market positioning by reducing product costs. However, acquisition cost, as well as quality and safety specifications, are of greater importance to manufacturers and customers, which may limit the environmental benefits obtained.