Social media marketing (SMM) plays an important role in business communication, marketing, operations, and other activities. There is a growing interest among researchers, academicians, and practitioners to understand the role of SMM in business sustainability in small and medium enterprises (SMEs) in an emerging economy, like India. Few studies have attempted to understand this role. Thus, the aim of this study is to examine the impact of adopting social media marketing for sustainable business growth of SMEs in an emerging economy. The study also investigates the moderating role of SME leadership support on the relationship between SMM usage and sustainable business growth of SMEs. After reviewing the existing literature and technology adoption model, a theoretical model is developed, which is then validated using a structural equation modeling technique to analyze 304 samples of Indian SMEs that use different social media marketing applications in their enterprises. This study confirmed that SMM tools significantly and positively improve the sustainable growth of SMEs in an emerging economy. Additionally, the study also found that SME leadership team plays a vital role in supporting actual usage of SMM tools that accelerate sustainable business growth of SMEs.