In the context of individual investors, financial decision-making has been explained through a complex mix of socialization, knowledge, and psychological processes, but little research clarifies the sequence of influences in determining individual investor investment outcomes. The research aims to identify the mediation between the financial socialization and the investment decision of the selected investors by way of financial literacy, investor perception, and behavioral bias. This research adopted a quantitative, cross-sectional research design, and primary data were obtained from investors through a structured questionnaire with five Bias and Investment Decision. Confirmatory Factor Analysis has validated the strong measurement validity and reliability for all constructs. A serial mediation analysis, preceded by the Hayes' Process macro (Model 6), indicated that the pathway of Financial Socialization – Financial Literacy – Investor Perception was the most significant and viable route that predicted Investment Decisions, accounting for the $4.00(5%) variance between the first and second steps. Contrary to expectations, Behavioral Bias was not seen to play a significant mediating role for the relationship and was associated to none of the other constructs, suggesting that behavioral biases are not extensions, but operate as independent mediators from the socialization-literacy-perception pathway. This refinement, and not the originally proposed full mediation chain, is the main empirical contribution of this study. They shed light on the boundary conditions of serial mediation models in behavioral finance and provide implications for financial educator design and financial policy design for literacy interventions that can augment the cognitive-perceptual path to investment decision-making