This study pioneers the development of the Sustainable Product Impact (SPI) Index, a novel framework designed to bridge the gap in existing sustainability assessment methodologies by focusing specifically on the influence of sustainable product development on a firm’s financial outcomes. For the first time, this research draws on the core principles of economics, marketing, and environmental sciences research fields to provide a comprehensive tool that enables businesses to quantify the multifaceted impacts of their sustainability initiatives within a corporate context. The SPI Index is an innovative metric that evaluates various factors, including financial and market performance, operational efficiency, brand perception, regulatory benefits, and long-term strategic advantages. This holistic approach allows for a more nuanced understanding of how sustainable practices influence a company’s bottom line and overall market position. Key findings of this research reveal that integrating sustainable product development into business strategies enhances environmental stewardship and impacts financial performance. The SPI Index has demonstrated its capacity to provide detailed insights into the specific areas of sustainability that most strongly affect profitability, thereby guiding businesses in their strategic planning and decision-making processes. In terms of originality and value, this study contributes to the existing body of knowledge by offering a unique and practical tool for businesses. The SPI Index stands out in its ability to translate sustainability efforts into quantifiable financial metrics, promoting a more integrated and balanced approach to corporate sustainability and profitability. Hence, this research plays a crucial role in guiding companies toward responsible corporate citizenship while focusing on economic viability in the modern business landscape.