["Journal of Product Innovation Management, EarlyView. ", "\nABSTRACT\n\nAcademic Summary\nThe prominence of environmental issues among consumers has led to the rapid development and launch of sustainable product innovations (SPIs). Developing SPIs can yield favorable financial outcomes for companies, but introducing these innovations requires major investments, while returns are highly uncertain. At the same time, positive consumer perceptions of SPIs are imperative for their success. Prior research suggests that SPIs with a higher degree of innovativeness experience faster innovation adoption. However, empirical research on the impact of radical versus incremental SPIs on consumer perceptions and the underlying mechanisms explaining these perceptions is scant. Drawing on attribution theory and conducting four consumer experiments and one meta‐analysis, we examine whether and how consumers make internal and external attributions about companies' motivations behind introducing SPIs. The findings reveal that radical (vs. incremental) SPIs result in favorable consumer outcomes because consumers attribute intrinsic motivations to companies introducing such innovations, a relationship moderated by companies' sustainability reputation. In contrast, attributions of companies' extrinsic motivations do not play a significant role in this regard. This study contributes to the literature on the impact of SPI on consumer perceptions and outcomes. Furthermore, it provides managerial guidance to companies intending to introduce SPIs.\n\n\nManagerial Summary\nAs environmental concerns grow, companies are under increasing pressure to develop sustainable products. Yet, not all sustainable product innovations (SPIs) are created equal and how consumers respond depends heavily on the type of innovation a company introduces. This research shows that radical SPIs (those that use entirely new technologies to create a sustainable product or to embed sustainability as a core product attribute) outperform incremental ones (those that modify existing products to improve eco‐efficiency, replace harmful materials, or enhance recyclability) across a range of outcomes that matter to business: purchase intentions, willingness to pay, perceived company authenticity, and overall attitudes toward the company. The key reason is that consumers interpret radical SPIs as driven by genuine environmental commitment, whereas incremental changes are seen as business‐as‐usual responses to competitive or regulatory pressure. For managers, this means that investing in truly transformative sustainable innovations pays off not just environmentally, but commercially. Equally important is a company's sustainability reputation: firms with an established track record of environmental responsibility amplify these positive effects, as consumers are more likely to trust their motives. For policymakers, incentivizing radical sustainable innovations creates a twofold benefit, real ecological impact alongside stronger market performance.\n\n"]