This review (with 141 refs) summarizes the state of the art in the preparation, electrocatalytic and electrochemical sensing applications of 3D porous nanomaterials derived from noble metal-based alloys. The introduction discusses the significance of such materials as electrocatalysts in fuel cells and electrochemical sensors due to their specific advantages. The next large section covers strategies to fabricate nanoporous noble metal-based alloys (including chemical dealloying and electrochemical dealloying, templated-based methods and assembly methods). We then review representative applications of nanoporous noble metal-based alloys in electrocatalysis in fuel cells (methanol, ethanol, formic acid and oxygen). A final section covers electrochemical sensors for small biomolecules (glucose, hydrogen peroxide, dopamine, ascorbic acid, uric acid, nitrite, drugs, etc.). Representative Tables are given that provide a rapid overview on the numerous kinds of materials and applications. A concluding section summarizes the current status, addresses current challenges, and gives an outlook on potential future trends. Graphical abstract Schematic representation of synthesis and applications of nanoporous noble metal-based alloys. The preparation methods include dealloying, templated and assembly method. The unique porous structure and synergistic effect among alloy atoms greatly enhance their electrocatalytic activity and electrochemical sensing ability.