Antimicrobial resistance (AMR) poses major therapeutic challenges, particularly in chronic biofilm-associated infections. Using a murine Pseudomonas aeruginosa biofilm lung infection model, we previously demonstrated rapid ciprofloxacin (CIP) resistance emergence after two administrations in one day, primarily via efflux pump regulator mutations. Here, we investigated resistance evolution under extended CIP exposure (four administrations over two days post-infection). Increased dosing accelerated resistance development, resulting in elevated minimum inhibitory concentrations (MICs). Resistance evolved through an initial mutation-driven tolerance phase, followed by full resistance associated with concurrent mutations in nfxB (efflux pump regulator) and gyrA (CIP target), consistent with clinical CIP-resistant isolates. Notably, high CIP MICs correlated with collateral sensitivity to tobramycin and aztreonam, revealing a trade-off in resistance pathways. Host response analysis showed elevated cytokine levels in early passages compared to later ones, and histopathology revealed strong neutrophilic inflammation and goblet cell development in untreated mice, resembling clinical biofilm lung pathology. CIP treatment attenuated inflammatory responses. Collectively, this optimized in vivo biofilm lung infection model captures both AMR evolution and host-pathogen dynamics, offering a valuable platform for translational research and the development of novel therapeutic strategies against biofilm-associated lung infections.