This article discusses a procedure of mixed methods sequential explanatory design used to conduct sequential QUAN → QUAL mixed methods study. The methodological procedures are explained using a mixed methods study of innovation in the Australian Public Service (APS). The sequential explanatory design incorporated quantitative and qualitative approaches in two consecutive phases within one study. The quantitative method (i.e. questionnaire survey) was conducted in the first stage, followed by the qualitative approach using thematic analysis. The questionnaire survey data to be complemented by an archival analysis approach under a two-phase analysis. The archival analysis provided fresh context to understand the innovation process in the APS. The findings from both phases of the study were then examined and combined to draw the conclusions. This study made several contributions to the body of knowledge related to research methodology by not only adopting a quantitative-dominant mixed method approach, but also by employing integrated methods used for a deeper understanding of the impact of socio-psychological constructs on workplace innovation and career satisfaction.