Our research investigates the intricate challenges organizations encounter when integrating sustainability into their business. Specifically, we mobilize paradox theory to analyze how SMEs manage paradoxes during their transformation towards sustainability. Our study, based on a longitudinal study of a small consulting firm undergoing B-Corp certification, revealed tensions arising from the paradoxes of performing, learning, organizing, and belonging. Our findings indicate that attempts to resolve a paradox can generate unexpected consequences and additional tensions. This research contributes to the existing body of literature on sustainability paradoxes, providing insights into the cascade of paradoxes triggered by transformation towards sustainable development.