The effects and underlying mechanisms of aging treatment on the microstructure and properties of Cu−0.3Be−2.0Ni and Cu−0.3Be−2.0Ni−0.2Al alloys (subjected to solid solution treatment followed by 70% cold rolling) were investigated. Results showed that the Cu−0.3Be−2.0Ni alloy mainly precipitated the Ni−Be phase, while the Cu−0.3Be−2.0Ni−0.2Al alloy exhibited co-precipitation of both Ni−Be and Ni₃Al phases. The combined strengthening from nanoscale Ni₃Al and Be−Ni phases significantly increased the strength of the Cu−0.3Be−2.0Ni−0.2Al alloy compared to the Cu−0.3Be−2.0Ni alloy. Thermo-mechanical treatment improved both the hardness and electrical conductivity of the alloys. Compared with conventional aging, the Cu−0.3Be−2.0Ni−0.2Al alloy showed a 13% increase in hardness and a 6.8% increase in electrical conductivity, while the Cu−0.3Be−2.0Ni alloy exhibited a 6% hardness increase with slight conductivity improvement.