Depressive disorders are highly prevalent in the working population and lead to excessive costs. Online interventions have shown to be effective treatments for depression but are not often applied in the work setting, despite the importance of work related aspects in the development and perpetuation of depression. We developed a worker-directed web-based intervention for employees with depressive symptoms named Happy at Work. A process evaluation was conducted alongside a randomized controlled trial to assess the feasibility of the intervention and to explore barriers and facilitators for further implementation of the intervention. Employees from different companies in the Netherlands who experienced elevated depressive symptoms and were not on sick leave were eligible to take part in this study. Happy at Work contains six lessons and every lesson has several assignments. When completed, a coach provides feedback to assignments via the website. Process measures investigated were: reach, dose delivered, dose received, and fidelity. Recruitment methods and participant satisfaction with the intervention were described and analyzed as well. Data was collected at baseline and 8. weeks later via online questionnaires and data registrations on the website. The implementation score of the intervention was sufficient, but reach of the target population was low. The dose delivered was high, with 93.1% of participants who used the intervention components that were offered to them. However, adherence to the intervention was low; the dose received was 57.8%. The fidelity of the implementation of the intervention was satisfactory. Recruitment of companies and participants was difficult. Participants were satisfied with the different aspects of the intervention, especially with the feedback from the coach. The results of this process evaluation showed that the intervention was conducted according to protocol and seems feasible for further implementation. Potential barriers to further implementation of the intervention include the reach of the target population, intervention adherence and the quality of the feedback. Based on the results of the effectiveness of the intervention, we do not recommend further implementation of the intervention in its current form.