INTRODUCTION: Psychotherapies delivered via the Internet have been promoted as an alternative for improving access to psychological treatments. A conceptual working alliance model of blended (i.e., traditional face-to-face consultation combined with Internet-delivered psychotherapy) cognitive-behavioral therapy (b-CBT) for depression has been developed in the UK. However, little is known about how this important therapeutic process, namely the working alliance (WA), is developed and maintained in Internet-delivered cognitive-behavioral therapy without face-to-face consultation (i-CBT). The aim of this study was to evaluate the validity of the WA model of b-CBT in Spanish patients with depression receiving i-CBT. METHODS: Forty-one patients suffering from mild-moderate depression were interviewed to assess their experiences of an i-CBT program. Interviews were conducted with participants who received a self-guided application (n = 9), and low-intensity support (n = 10). Three group interviews were also conducted with patients who either did not start the program (n = 8) or did not complete it (n = 6), and with patients who did complete it (n = 8). RESULTS: Qualitative thematic content analysis was performed using the constant comparative method, which revealed four main themes: "bond," "goals," "task," and "usability heuristics," all consistent with the existing literature. However, a new subcategory emerged, called "anonymity," which may highlight the social stigma that mental illness still has in the Spanish context. CONCLUSION: Results suggest that the development and maintenance of the WA through i-CBT could offer a better experience of the therapeutic process and improve the clinical impact. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov, identifier: NCT01611818.