Energy efficiency is undeniably an important contributor to energy sustainability. It mirrors the ‘low hanging fruit’ in which energy efficiency is one of the easiest ways to reduce energy demand. Small and medium-sized enterprises (SMEs) can make a major positive contribution to energy sustainability and community well-being, given the extent of their involvement in the economy. This research attempts to explore SMEs’ perceptions towards energy efficiency investment. Specifically, this research examines the effects of senior managers’ perceived benefits, perceived costs and personal norms on their support for energy efficiency investment. A survey was conducted to collect data and empirically test the research model. The estimated results suggest senior managers’ perceived benefits and costs significantly affect their support for energy efficiency investment. In addition, the results show that personal norms are an important mediator variable in influencing energy efficiency investment by SMEs. Several notable implications can be drawn from this research. The findings demonstrate the undeniable significant effects of perceived benefits and costs on firm investment decision-making and do not neglect the importance of personal norms.