pH-responsive nanogels, also called as pH-sensitive nanogels, pH-triggered nanogels, smart nanogels, intelligent nanogels or environment-sensitive nanogels w.r.t. pH are presently undergoing extensive research and development as drug delivery systems. They are cross-linked polymeric networks sensitive to small changes in pH leading to large-scale volume phase transition. They are fabricated by incorporation of pH-sensitive polymers or pH-sensitive linkers within their architecture. A wide variety of natural polymers sensitive to pH are available in the nature such as Alginic acid, Carrageenan, Cellulose, Chitin, Chitosan, Dextran, Dextrin, Guar gum, Hyaluronic acid, Pullulan and Xanthan gum. They are more biocompatible and biodegradable than the synthetic polymers and also relatively cheaper, non-toxic with a high content of functionality. Compared to the conventional targeting methods, the pH-triggered strategy using pH-responsive nanogels loaded with pH-responsive natural polymers is considered to be more general as the drug release kinetics are modulated by pH variations in cancer, psoriasis, infection, inflammation and ischaemia whereby various organs and tissues are accompanied with local pH changes. This review primarily highlights the synthesis, pH-responsiveness and applications of pH-responsive nanogels fabricated from naturally occurring pH-responsive polymers. The novel development of pH-responsive nanogels illustrated here provides tremendous potential for accomplishing exceptionally superior therapeutic results.