This chapter presents natural nanomaterials—nanoclinoptilolite, nano-kaolin, nano-alum, perlite, chitosan, and magnetite—as efficient, low-cost, and environmentally friendly materials for water purification. This chapter examines their synthesis, surface modifications, and performance in adsorption and photocatalysis, drawing on experimental results and case studies from the author’s research. Key highlights include copper- and cobalt-modified nanoclinoptilolite sorbents, zinc oxide nanoclinoptilolite photocatalysts, nano-kaolin and nano-alum systems for both adsorption and photocatalysis, as well as perlite, chitosan, and magnetite as multifunctional sorbents and photocatalysts. Mechanisms of pollutant capture, photodegradation pathways, surface interactions, and structure–property relationships are discussed in detail. This chapter concludes with a critical evaluation of current challenges and future research directions, providing a road map for the further development of natural nanomaterials in environmental remediation.