In this study, we examine the direct relationship between business digitalisation and improvements in economic sustainability, as well as the potential mediating role of environmental sustainability. We also examine the potential role of company size as a moderating variable in these relationships. We gathered data from micro, small and medium‐sized enterprises (MSMEs) in Finland. Contrary to initial expectations, our findings reveal that there is no direct and significant relationship between business digitalisation and the economic sustainability of enterprises; this relationship is only possible through the mediating role of environmental sustainability. We also found that, although high levels of environmental sustainability may result in improved economic outcomes, the strength of this relationship is much weaker for microenterprises than for their larger counterparts. Altogether, these results underscore the complex interplay between digitalisation and sustainability outcomes within the context of small businesses.