This chapter presents and discusses sustainable fertilizers for a more sustainable agriculture, considering that fertilizers are pivotal in modern agriculture to promote crop production to meet the global demand for food, feed, and fibers. However, their production and usage can generate negative impacts on the environment that need to be mitigated. Thereby, this outlook was structured by means of a critical evaluation of the market, the most widely used fertilizers, raw materials and industrial production, environmental potential impacts, aspects of plant nutrition and soil chemistry, and the main types of sustainable fertilizers. From these contents, conclusions and perspectives were duly pointed out and explored, reinforcing the strategic role of these fertilizers to modern agriculture.