Multiple job holding (MJH) or holding more than one job along with a primary job, though not a new phenomenon, has witnessed renewed interest due to recent trends within the changing career systems. Studies on MJH, so far, have (over)emphasized the individual motivations to hold multiple jobs while largely understating the role of contextual influences including the institutional settings, legal regulations, economic cycles, technological changes, and organizational contracts. The present study, employing the career ecosystem theoretical lens, systematically reviews and identifies the range of factors operating at the individual, occupational, organizational, and environmental levels influencing MJH. Further, the top-down and bottom-up influences on MJH across these various levels are delineated. By embedding the individual multiple job holders within the wider ecosystem of interrelated stakeholders, the study highlights the complex interplay of factors influencing MJH. Implications for practice and suggestions for future research around multi-level antecedents of MJH are discussed.