This study conducts a quantitative assessment and comparison of the investment preferences of muslim millennial, focusing on riba free versus conventional financial products. The research further seeks to identify the primary determinants influencing these preferences, with an emphasis on religiosity, financial literacy, and factors derived from the Theory of Planned Behavior (TPB). A quantitative, cross-sectional survey methodology was employed, targeting Muslim Millennials which born between 1981 until 1996 residing in DKI Jakarta. Primary data were collected from a sample of 385 respondents through a structured online questionnaire. Key variables measured included investment preferences for both Sharia and conventional products. Data analysis involved descriptive statistics, validity and reliability testing, comparison test, and structural equation modelling-covariant based (CB-SEM) to see the influence. The results indicate a statistically significant preference among DKI Jakarta's Muslim Millennials for riba free investment products over conventional alternatives. Religiosity emerged as the strongest positive predictor of preference for riba free investments. Attitude towards Sharia investing and perceived behavioral control were also significant positive influences. Financial literacy exhibited a positive but relatively weaker significant effect, while subjective norms and risk tolerance did not significantly predict preference in the final model. The overall model explained a substantial portion of the variance in preference. This study contributes to the understanding of investment behaviors among Muslim Millennials in accordance with Islamic principles.