Digital marketing innovation plays an important role in a company’s performance. Since this concept is quite new, there are not many empirical studies on the impact of marketing innovations. The purpose of this study is to examine the impact of digital marketing innovation on firm performance, consider the mediation effect of marketing capability on the impact of digital marketing capability on firm performance and explore the potential moderating effect of firm size on the mediation effect. Using KOSPI and KOSDAQ data and a linear moderated mediation estimation, we found that digital marketing innovation on firm performance through marketing capability has significant direct and indirect effects, with indirect effects greater than direct effects. Theoretical and practical implications are also discussed in this article.