Penelitian ini bertujuan untuk meneliti pengaruh social media marketing, online advertising, electronic word of mouth dan brand awareness sebagai mediasi terhadap purchase decision di Shopee. Populasi dalam penelitian ini adalah pelanggan dari Shopee Indonesia yang tinggal di Provinsi DKI Jakarta dan menggunakan Shopee. Data primer dikumpulkan menggunakan metode kuesioner. Data tersebut dianalisis menggunakan Partial Least Square-Structural Equation Modeling approach dari software SmartPLS 3.0. Hasil penelitian menunjukkan bahwa social media marketing dan online advertising memiliki pengaruh negatif dan tidak signifikan terhadap brand awareness dan purchase decision. Hasil pengaruh negatif lainnya adalah Bramd awareness memediasi pengaruh negatif social media marketing dan online advertising terhadap purchase decision. Sebagai tambahan, electronic word of mouth memiliki pengaruh positif dan signifikan terhadap brand awareness dan purchase decision, dan brand awareness memiliki pengaruh positif dan signifikan terhadap purchase decision. Brand awareness juga memediasi secara positif pengaruh electronic word of mouth terhadap purchase decision./ This research aims to examine the influence of social media marketing, online advertising, electronic word of mouth and brand awareness as a mediation on purchase decision at Shopee. The population in this research are customers from Shopee Indonesia who live in DKI Jakarta Province and use Shopee. Primary data was collected using questionnaire method. The data were analyzed using Partial Least Square-Structural Equation Modeling approach of SmartPLS 3.0 software. The results of the research show that social media marketing and online advertising have a negative and insignificant effect on brand awareness and purchase decision. The result of another negative effect is that brand awareness mediates the negative influence of social media marketing and online advertising on purchase decision. In addition, electronic word of mouth have a positive and significant effect on brand awareness and purchase decision and brand awareness have a positive and significant effect on purchase decision. Brand awareness also positively mediates the influence of electronic word of mouth on purchase decision.