INTRODUCTION: Globally, about half of all pregnancies are unintended and/or unwanted and three-fifths of these end in induced abortion. When faced with a choice to terminate pregnancy, women's abortion decision-making processes are often complex and multiphasic and maybe amplified in low- and middle-income countries (LMICs) which bear the major burden of abortion-related morbidity and mortality. Our review aims to (1) describe abortion decision-making trajectories for women in LMICs and (2) investigate factors influencing the choice of abortion decision-making trajectories in LMICs. METHODS AND ANALYSIS: We will search and retrieve published and unpublished qualitative, quantitative and mixed-methods, community and/or hospital-based studies conducted in LMICs from 1 January 2000 up to 16 February 2021. We will search Ovid Medline, Ovid EMBASE, Ovid PsycInfo, Ovid Global Health, Web of Science (including Social Science Citation Index), Scopus, IBSS, CINAHL via EBSCO, WHO Global Index Medicus, the Cochrane Library, WHO website, ProQuest and Google Scholar. We will search reference lists of eligible studies and contact experts for additional data/information, if required. We will extract all relevant data to answer our research questions and assess study quality using the appropriate appraisal tools. Depending on the extracted data, our analysis will use sequential or convergent synthesis methods proposed by Hong et al. For qualitative studies, we will synthesise evidence using thematic synthesis, meta-ethnography or 'best-fit' framework synthesis; and for quantitative findings, we will provide a narrative synthesis and/or meta-analysis. We will do sensitivity analyses and assess confidence in our findings using Grades of Recommendation, Assessment, and Evaluation -Confidence in Evidence from Reviews of Qualitative Research (GRADE-CERQUal) for qualitative findings and Grades of Recommednation, Assessment, and Evaluation (GRADE) for quantitative findings. ETHICS AND DISSEMINATION: We did not require ethics approval for this systematic review. We will publish our findings in an open-access peer-reviewed journal with global and maternal health readership. We will also present our findings at national and international scientific conferences.