The high cost and poor thermal durability of current lean nitrogen oxides (NOx) aftertreatment catalysts are two of the major barriers to widespread adoption of highly fuel-efficient diesel engines. We demonstrated the use of strontium-doped perovskite oxides as efficient platinum substitutes in diesel oxidation (DOC) and lean NOx trap (LNT) catalysts. The lanthanum-based perovskite catalysts coated on monolith substrates showed excellent activities for the NO oxidation reaction, a critical step that demands heavy usage of platinum in a current diesel aftertreatment system. Under realistic conditions, La1-xSrxCoO3 catalysts achieved higher NO-to-NO2 conversions than a commercial platinum-based DOC catalyst. Similarly, a La0.9Sr0.1MnO3-based LNT catalyst achieved NOx reduction performance comparable to that of a commercial platinum-based counterpart. The results show promise for a considerably lower-cost diesel exhaust treatment system.