As procurement increases its influence across categories of spend, thus improving the spend-under-management -ratio, and achieves strategic involvement in digitalization and business development projects, it increasingly comes across situations where traditional sourcing processes do not produce optimal outcomes, and in the required time frame. Particularly, in situations where the specifications are difficult to determine, and the internal customer seeks solutions to problems or unique designs, a mature procurement organization may forego normal RFx methods and deploy a request-for-solution (RFS) method instead. Such approaches may be called agile sourcing, drawing on the agile project management paradigm, in which the focus is on sourcing solutions without up-front specifications, by the means of iterative co-development with suppliers. This working paper seeks to explore the phenomenon of agile sourcing, and provide initial insights to the following research question: What are the key principles and methods of agile sourcing? The topic is timely, as the wicked problems in our society call for procurement to provide solutions to major environmental and social challenges, and serving as a catalyst for systemic change. In terms of paper structure, the front-end theoretical section reviews the variety of sourcing processes in the purchasing and supply management literature, thus establishing the body of knowledge to which we seek to make a contribution. For example, the literature on sourcing processes in general and process for service sourcing in particular are examined. Furthermore, we consider the literature on agile project management, by exploring its key principles and its genome, and contrast it with the so called waterfall-type of project management. The next section of the paper describes the procedures undertaken to collect and analyse data for the single case study on the sourcing of the Finnair mobile app (the Finnish national carrier), involving three open and semi-structured interviews and examination of internal and external documentation of the project. Having received the Red Dot Design Award in 2016, and consistently receiving excellent reviews in the Apple Store, the app, and the associated sourcing project may be considered quite successful. Therefore, it represents an interesting case for exploring the phenomenon. The analysis section of the paper describes the process for agile sourcing of the mobile app, by breaking it down to its key steps and components, as well as by listing the key principles in execution, which are perceived to have been contributed to the success of the project from the procurement perspective. By incorporating the extant theoretical knowledge and insights form the empirical case study, we provide initial insights into the definition and principles of this novel type of sourcing process through which procurement may provide solutions to strategic challenges of the organization.