Promoting surface strains in heterogeneous catalysts and heteroatomic interactions in alloying offer an effective strategy for the development of electrocatalysts with greatly enhanced activity. In this work, we design platinum-silver nanotubes (PtAg NTs) with tunable surface compositions by a controlled galvanic replacement reaction of well-defined Ag nanowires (NWs). The optimized and porous PtAg NTs (PtAg-4 NTs), with the Pt5Ag3 surface composition and (111) facet-dominant surface features, exhibit an extraordinary oxygen reduction reaction (ORR) activity that reaches a specific activity of 1.13 mA cm-2 and a mass activity of 0.688 A mg-1Pt at 0.9 V versus a reversible hydrogen electrode (RHE), which are 4.5 times and 4.3 times those of commercial Pt/C catalysts (0.25 mA cm-2 and 0.16 A mg-1Pt). Moreover, PtAg-4 NTs/C can endure under the ORR conditions over the course of 10 000 cycles with negligible activity decay. Remarkably, density functional theory simulations reveal that the porous PtAg-4 NTs exhibit enhanced adsorption interaction with adsorbates, attributed to the catalytically active sites on high-density (111) facets and modulation of the surface strain, further boosting the ORR activity and durability.