The purpose of this study is to uncover the rationale (why) and the types of designs (what) for application of mixed method approaches in finance research using a systematic literature review approach. The findings revealed that there are four main research gaps in mixed method applications in finance: (a) poorly or nonformulated research questions, (b) lack of identification of the rationale for mixed methods, (c) poor identification of mixed methods and design, and (d) the manuscript reviewing gap. Finance studies based on quantitative methods and proxy variables can be further validated through mixed method approaches, thereby increasing the validity, completeness, and confirmation of findings, and minimizing the inherent weaknesses of mono-method approaches. We suggest that researchers in the finance discipline should justify their research methodology in order to eliminate the biases that arise through the selection of convenient methodologies. Thus, future studies should incorporate both qualitative and quantitative aspects when formulating mixed method research questions, emphasize the rationale, and choose appropriate mixed method designs to achieve a high level of scientific rigor in mixed methods research. Also, editors of nonmixed method journals need to have reviewing support from mixed method experts or adhere to the guidelines proposed by Onwuegbuzie and Poth when evaluating mixed method manuscripts to achieve a high level of quality and accuracy in their mixed methods research publications in finance.