This study investigates the effect of preliminary ultrasonic treatment on the flotation recovery of copper from aged tailings of copper porphyry ores. The initial sample was characterized by a low copper content of 0.17%, a high proportion of oxidized copper forms at 53.84%, and fine dissemination of copper-bearing minerals, which complicates their recovery by conventional flotation. Ultrasonic treatment was applied after grinding as a physical method of surface activation. The pulp was treated at a power of 30 W and a frequency of 22 kHz, while the treatment duration varied from 0 to 25 min. The effects of ultrasonic treatment on concentrate yield, copper grade, copper recovery, and enrichment efficiency were evaluated. One-way analysis of variance (ANOVA) was used to assess the statistical significance of the results, and SEM analysis was performed to examine changes in particle surface morphology. The best flotation performance was obtained after 15 min of preliminary ultrasonic treatment. Under these conditions, the copper grade in the concentrate was 1.79 ± 0.06%, copper recovery was 44.37 ± 0.21%, and enrichment efficiency was 40.06 ± 0.38%. Longer treatment times did not improve the results. SEM observations revealed morphological changes consistent with particle disaggregation and possible partial cleaning of mineral surfaces.