The design and study of lanthanide-based compounds as a substantial category of materials that possess distinguished characteristics are of interest for a large number of scholars in recent times. They have illustrated helpful and notable applications in a variety of fields, markedly in environmental remediation. There are a variety of approaches for preparing lanthanide-based compounds. This chapter introduces the diverse approaches for synthesizing lanthanide-based compounds owing to special technological importance of this category of compounds. The advantages and drawbacks of each approach for synthesizing are briefly expressed. At last, applications of lanthanide-based compounds for environmental remediation are highlighted.