In recent years, large-scale acquisitions of startups by platform firms have drawn significant attention from global antitrust authorities and academia, making “killer acquisitions” one of the most debated topics in competition policy. This paper systematically reviews the literature on killer acquisitions by platform firms, presenting the current state of research and academic controversies across four dimensions: conceptual definition, driving factors, competitive effects, and antitrust regulation. The findings reveal that while a basic consensus has emerged on the definition of killer acquisitions—where incumbent firms acquire innovative startups to eliminate potential competitive threats—there remains a risk of conceptual overextension when applying this notion to the digital platform context. Regarding driving factors, eliminating potential competitive threats is the core explanatory variable, yet ecosystem building, talent acquisition, and data hoarding are also significant and multifaceted motives. Empirical evidence on competitive effects is highly divergent: international studies tend to confirm the anticompetitive harm of killer acquisitions, whereas empirical research based on China’s BAT companies (Baidu, Alibaba, Tencent) finds no consistent “killer” motive, highlighting notable contextual differences between Western and Chinese platform markets. Antitrust regulation faces three major challenges—ineffective merger notification thresholds, difficulty in identifying potential competition, and a heavy burden of proof. Various jurisdictions are exploring regulatory reforms by introducing transaction-value thresholds, ex post review mechanisms, and shifts in the burden of proof. Based on these insights, this paper identifies four promising directions for future research: modeling the dynamic competitive effects of killer acquisitions, comparative institutional analysis of platform merger patterns between China and the West, strategic combinations of regulatory tools and welfare trade-offs, and the evolving forms of killer acquisitions in the AI era alongside corresponding policy responses.