Research into green product purchasing behavior has received significant attention in recent years, especially as global environmental concerns have continued to grow. However, holistic studies on what drives consumers to purchase green products—which usually come with premium prices—are still needed. This study addresses this gap by examining both internal and external drivers that influence consumers’ willingness to pay more and their actual purchase behavior in the context of green cosmetics in Indonesia. Internally, we focus on personal norms, while externally, we investigate the roles of ethical marketing perceptions and green future estimation. We collected data from 460 respondents in Indonesia via purposive sampling via online questionnaires. We analyzed the data via partial least square-structural equation modeling (PLS-SEM) with the support of SmartPLS version 4. This finding shows that the examined predictors, ethical marketing perceptions exert the most substantial influence on consumers’ willingness to pay premium prices for green cosmetics, surpassing the effect of internal personal norms. Meanwhile, the perceived estimation of a green future has the least impact. Furthermore, willingness to pay more has a significant and positive direct effect on actual green purchase behavior, with a strong effect size that supports the generalizability of our results. To test the consistency of these findings across different demographic groups, we conducted an ANOVA test, which confirmed the robustness of our model across generational cohorts. We make a new contribution to the norm activation model theory by adding an external perspective toward explanatory findings in consumers’ purchase behavior of sustainable products. Copyright (c) 2025 The Authors. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.