Cancer is considered highly mortal due to the frequency of late diagnosis, usually in advanced stages. Early diagnosis plays a pivotal role in reducing mortality and improving prognosis of the disease. An alteration in glycans is the hallmark of cancer. In last two decades, there has been an exponential increase in the use of lectins to mark the foremost challenging problem of detection and therapy in cancer. Plant lectins have an ability to specifically and selectively bind and target to glycosylated biological molecules with good sensitivity. This property of lectins has shown them to possess a promising and potential application within the field of cancer detection and therapy. Lectins are a special class of proteins of non-immune origin which selectively recognize and reversibly bind to carbohydrates and glycoconjugates. The aim of present paper was to discuss the current status of lectins and their nano-structures studied so far for detection and therapy of various cancers. Lectins serve as the major molecular tools for glycan profiling. Their application as nano tools is getting impedance for the diagnosis and treatment of cancer. Lectin conjugated drug delivery systems are recognized, bound, and internalized by aberrant sugar present on the cancerous cell surface. Lectins adhere to neoplastic cell membrane and cause apoptosis-induced cytotoxicity to trigger autophagy or necrosis in cancer cells without affecting the normal cells. Cytotoxicity of Nano-Lec-materials displays impressive anticancer effects in addition to early detection. Drug delivery to targeted sites using engineered nano-lectins allows enhanced efficiency and reduced toxicity to normal cells and thus improved patients’ quality of life. The present review will describe the current status of lectins and glycoconjugates in cancer detection and their applications as nano-materials in future therapeutics as drug carriers against many diseases and effective cancer targeting bullets.