This research analyzes the impact of a regional brand ambassador and social media advertising on the brand trust and brand loyalty of Lazada, an online marketplace in Indonesia, directly and indirectly. The statistical technique is SEM-PLS to analyze 100 data using convenience sampling. The results show that social media advertising impacts brand trust directly and indirectly, and only brand trust impacts brand loyalty, while the regional brand ambassador does not impact brand trust or brand loyalty directly and indirectly. It implies that Lazada needs to do in-depth research to analyze the right brand ambassador that suits customers' preferences and produces more engaging advertising content to increase brand trust and build brand loyalty.

Social Media is one of the digital marketing media that is widely used today and the presence of the brand ambassador phenomenon is one of the determinants of consumer purchasing decisions for a product advertised on social media. In today's advances in digital technology, whether consumers prefer to be a model for the product and also whether trust in consumers is also a factor in the consumer's decision to buy. The purpose of this study is to examine the effect of brand ambassador and trust variables on consumer decisions to shop online and also purchase decisions on repurchase. In this study the researchers used four variables, twelve dimensions where each dimension was represented by two indicators so that in this study there were twenty-four indicators which would later be changed in the form of questions to respondents. The population used is consumers who have shopped for fashion products using brand ambassadors. Given that the population is very large, the researchers used quota sampling to determine the number of samples. The study used 5 times the number of indicators so that there were 120 samples of respondents who were processed through Structural Equation Modeling analysis techniques with AMOS software. The results of data processing indicate that brand ambassadors and trust significantly influence consumer purchasing decisions. It was found that trust had the greatest influence on trust. Moreover, purchasing decisions have a significant effect on online consumer repurchase.