As our world is getting increasingly servitized and digitized, innovation is no longer bound to physical products. Customer experience and innovative services have become the new imperative for business success. Design Thinking is becoming a valid approach for service innovation in the digital age. However, a profound understanding of “how” Design Thinking contributes to service innovation is still missing. We show this by conducting a Delphi study which includes 14 Design Thinking experts across different company sizes and industries. As a result, we demonstrate consensus on 59 highly relevant methods for service innovation allocated to the respective Design Thinking phase. This is the first study to provide a comprehensive view on Design Thinking methods for service innovation. We enhance the understanding of Design Thinking and lay the foundation for further investigations into the service innovation process. Practitioners receive guidance from our findings for applying those methods.