4^th International Conference on Big Data and Machine Learning (BDML 2021) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of Big Data and Machine Learning. The Conference looks for significant contributions to all major fields of the Big Data and Machine Learning in theoretical and practical aspects. The aim of the conference is to provide a platform to the researchers and practitioners from both academia as well as industry to meet and share cutting-edge development in the field.