With escalating resistance to antibiotics there is an urgent need to develop alternative therapies against bacterial pathogens. Phage therapy has been proposed as a promising alternative to antibiotics, but an increasing number of studies suggest that both of these antimicrobial agents in combination are more effective in controlling pathogenic bacteria than either alone. Despite an increased understanding of how phages interact with bacteria, we know very little about how their interactions may be modified in antibiotic environments and, reciprocally, how phage may affect the evolution of antibiotic resistance. We experimentally evaluated the impacts of single and combined applications of antibiotics and phages on in vitro evolving populations of the opportunistic pathogen Pseudomonas aeruginosa PAO1. We found a strong synergistic effect of combining antibiotics and phages on bacterial population density and in limiting their antibiotic resistance levels. When testing co-evolutionary dynamics between phages and bacteria we found that they were influenced by antibiotics in some degree. Interestingly, a quantitative analysis of “evolved phages” effect on “ancestral bacteria” showed that antibiotics increased phage infectivity compared to non-antibiotic treatments, suggesting that antibiotics can impact the evolution of phages. From an applied perspective, our results indicate that phages can contribute to managing antibiotic resistance levels and that antibiotics can promote phage adaptation. We discuss the relevance of our findings for future research aimed at treating bacterial infections in human health care.