Background. In the MasterMind project, Internet-based Cognitive Behaviour Therapy (iCBT) services for depression have been implemented in routine care in 14 European regions. This study aimed to advance understanding of the nature and value of organisational implementation climate in implementing iCBT services from the perspectives of implementers and service deliverers.Methods. A mixed method approach was applied. Based on principles of concept mapping, a structured workshop with implementers was conducted to qualitatively conceptualise organisational implementation climate conducive to optimizing iCBT use in routine practice. Mental health service delivers involved in the provision or referral of patients to the implemented iCBT services were invited to participate in a cross-sectional survey assessing levels of satisfaction and usability of iCBT, and organisational implementation climate. Associations between satisfaction, usability and implementation climate were explored.Results. 16 implementers representing 14 service delivery organisations participated in the workshop. The top-3 characteristics of a strong organisational implementation climate included: (1) clear roles and skills of implementers, (2) feasible implementation targets, and (3) a dedicated implementation team. The top-3 tools for creating an implementation climate included: (1) job performance feedback, (2) progress monitoring in relation to achieving implementation targets, and (3) guidelines for assessing the impact of iCBT. In total 111 respondents (73% female) completed the survey. Mental health service deliverers were generally satisfied delivering iCBT services (MCSQ = 9.11, SD = 1.96, range = 3-15, n = 108) and found their usability slightly below average (MSUS = 63.76, SD = 15.53, range = 0-100, n = 103). They regarded their organisational implementation climate as supportive in implementing iCBT services (MICS = 43.21, SD = 5.62, range = 12-60, n = 89). Organisational implementation climate was weakly associated with the system usability scale (r = 0.25, p =.03) and moderately with the satisfaction scale (r = .51, p £ .00).Conclusions. Organisational implementation climate as part of the wider organisational context in which implementation processes take place, is a relevant factor to implementers and service deliverers in implementing iCBT in routine care. The qualitative conceptual findings align with the quantitative approach applied in this study for measuring organisational implementation climate. Implementers can use various practical tools to shape organisational implementation climate to increase acceptance and subsequently improve implementation of iCBT in mental health care.