The constant studies developed in research into biofertilizers from microalgae have generated enormous knowledge of the various advantages that these presents in agriculture, improving the fertility and quality of the soil and plant growth and the environment. The constant use of biofertilizers is presented as an alternative to reducing the use of chemical fertilizers and reducing their impact on the environment. Biofertilizers could allow bioremediation and reduce the loss of arable land, allowing soils considered infertile to recover their properties economically and more sustainably. According to these considerations, microalgae, due to their functional characteristics, rapid growth, and ease of reproduction, have gained important attention worldwide as a biological source for the development of biofertilizers. This chapter provides an overview of using novel microalgae as biofertilizers and soil improvers. In addition, the current strategies that have been developed to optimize the obtaining of biofertilizers from microalgal cultures for advanced agriculture are specified.