Financial knowledge and financial attitude are important dimensions of individual financial decision-making, particularly in investment contexts where investors need to evaluate information and make informed choices. Within this context, this study investigates the association between financial knowledge and investor confidence, as well as the relationship between financial attitude and mutual fund investment decision quality among retail investors in Thiruvananthapuram district. To evaluate the relationships between variables, this study gathered primary data from 287 retail mutual fund investors utilising a structured questionnaire through purposive sampling within a quantitative, cross-sectional, and explanatory framework. Data were examined using reliability testing through Cronbach’s alpha, exploratory factor analysis, descriptive statistics, alongside Spearman’s and Kendall’s Tau-b correlations, simple linear regression, and ordinal logistic regression. The results demonstrated a strong positive association between financial knowledge and investor confidence (ρ = 0.584, p < 0.001), where financial knowledge accounted for 34.1% of the variation in confidence. Financial attitude also showed a significant positive association with mutual fund investment decision quality (τb = 0.467, p < 0.001). The ordinal logistic regression model yielded a Nagelkerke R² of 0.286, indicating the model’s explanatory capacity for the ordered levels of investment decision quality. The empirical evidence highlights the significance of financial knowledge and financial attitude in understanding different dimensions of mutual fund investment decision-making.