In the last decade, gold and silver nanomaterials have received considerable attention due to their attractive electronic and chemical properties and their potential applications in the development of new technologies. Recent advances in the study of various gold and silver nanomaterials have led to their utilization in a number of very important applications including biosensing, diagnostic imaging, and cancer diagnosis and therapy. This review surveys the various synthetic methods of gold and silver nanomaterials. Recent experimental studies focusing on the use of gold and silver nanomaterials in catalysis, food industry, and environmental conservation are also reviewed. This review also highlights the advantages of gold and silver nanomaterials in the development of fluorescence biosensors, glucose biosensors, nucleic acids-based biosensors, and protein-based biosensors. Moreover, the potent in vitro and in vivo anti-microbial and cyto-genotoxic effects of various gold and silver nanomaterials are underlined. Finally, recent advances in the employment of gold and silver nanomaterials as effective drug delivery vehicles and promising cancer therapeutic agents are summarized. Despite their use in remediating numerous medical and health-related conditions, the efficacy and safety of many gold and silver nanomaterials is still under some scrutiny. Needless to say, researchers are facing many challenges and obstacles in their ample attempts to synthesize nanomaterials that are relatively easy to design, inexpensive to fabricate, and effective in treating various diseases, but at the same time display a very low, if any, toxicity to the body. Future investigations should aim at overcoming such challenges in an attempt to design nanomaterials that will prove to be useful in diagnosing and treating life-threatening diseases while ensuring a high degree of efficacy and safety.