Rationale, aims and objectives Clinical pathways (CPs) can improve quality of care on intensive care units (ICUs), but are infrequently utilized and of varying quality. Knowledge regarding factors that facilitate versus hinder successful implementation of CPs is insufficient and a better understanding of the activities and individuals involved is needed. The aim of this study was to explore the implementation process of CPs within the context of ICUs. Methods An exploratory design with a sequential mixed method was used. A CP survey, including all Swedish ICUs, was used to collect quantitative data from ICUs using CPs (n = 15) and interviews with key informants (n = 10) were used to collect qualitative data from the same ICUs. Descriptive statistics and qualitative content analysis were used, and the quantitative and qualitative findings were integrated. Results The CP implementation was conceptualized according to two interplaying themes: a process to realize the usefulness of CPs and create new habits; and a necessity of enthusiasm, support and time. Multiple factors affected the process and those factors were organized in six main categories and 14 subcategories. Conclusions Bottom-up initiatives, interprofessional project groups and small ICUs seem to enhance successful implementation of CPs while inadequate electronic health record systems, insufficient support and time constrains can be barriers. Support regarding the whole implementation process from centralized units at the local hospitals, as well as cooperation between ICUs and national guidance, has the potential to raise the quality of CPs and benefit the progress of CP implementation.