Microplastics (MPs) have emerged as widespread pollutants entering aquatic environments worldwide, posing significant threats to ecosystems and human health. Wastewater treatment plants (WWTPs) are critical points in the journey of microplastics from urban and industrial sources to natural water bodies. Yet, the complexities of detecting and quantifying these microscopic particles in such challenging mixtures remain a serious barrier to effective monitoring and mitigation. This chapter systematically examines the MP analytical workflows in wastewater and sludge, focusing on three critical aspects: sampling strategies, pretreatment methods, and detection techniques. The chapter explores sample collection and preservation protocols across different wastewater matrices, emphasizing quality control measures essential for reliable analysis. It critically assesses pretreatment approaches, including wet peroxide oxidation, enzymatic digestion, chemical treatments, and density separation techniques using various solutions (ZnCl2, NaCl, NaI). Filtration methods are examined with particular attention to material selection and efficiency considerations. The integration of these preparation steps with subsequent analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) is discussed through practical decision frameworks and validated protocols. The chapter concludes by addressing current methodological challenges, including standardization issues and detection limitations, alongside emerging solutions. By synthesizing recent developments and practical considerations, this chapter serves as a comprehensive guide for method selection and optimization in wastewater microplastic analysis. It also highlights future directions for analytical advancement and provides forward-looking perspectives on emerging technologies.