Initial Public Offerings (IPOs) represent a pivotal event in financial markets, often generating effects that extend beyond the issuing firm. These externalities are visible from the issue-filing stage and can be traced into the long run after listing, and are collectively termed as spillover effects, manifesting across its business partners, industries, markets, and other related parties, and have attracted increasing scholarly attention over the past two decades. This study conducts a systematic literature review, employing content analysis of 47 peer-reviewed articles published up to April 2025 across the Scopus database, to synthesise existing research on the spillover effects associated with IPOs, aiming to identify key themes and their impact. The analysis reveals diverse spillover mechanisms, such as information, competitive effect, geographical, supply chain, economic and other miscellaneous effects, that result in disclosure prompts, IPO encouragement, entrepreneurship promotion, valuation effects on industry peers, and other outcomes. The review also identifies important gaps, such as a lack of studies on emerging markets and an ambiguous definition of "spillover." This paper contributes to the literature by offering an integrated framework for understanding IPO-induced spillovers and provides recommendations for future research. The findings have practical implications for investors, policymakers, and financial analysts seeking to anticipate and respond to the broader market impacts of IPO activity and existing firms that can leverage or defend against the consequences of new entrants.