Social media penetration is on the rise in developing countries and is an important channel of growth for small and medium enterprises (SMEs). Many SMEs in developing countries use social media to connect their customers to their products and services. However, the factors that have led the existing SMEs in Africa to adopt or reject social media need to be clarified to understand the key contributing factors and influences at play. This paper adopts the learning-by-doing concept from economic theory to explore the factors that influence the adoption of social media. A primary survey follows this to examine the use of social media among firms in the commercial districts of Kenya and Nigeria. The preliminary surveys in both countries were combined into a single dataset to analyse the relationship between social media use and learning-by-doing.The results show that while small SMEs are limited in their social media capacity, medium size firms tend to invest in their social media presence, and larger-size firms still rely on traditional marketing channels.