Pulmonary fibrosis is an interstitial lung disease characterized by irreversible scarring of lung tissues, but its root cause remains to be discovered. Understanding the related cofactors and comorbidities is difficult due to their intertwining with other fatal diseases, infections, and significant exposure to hazardous materials, which hinders the development of anti-fibrotic drugs. Advanced 3D tissue models offer insights into elucidating lung pathophysiology and serve as invaluable tools for drug toxicity screening. These models outrank 2D cell culture by faithfully replicating architectural complexities, revealing cell behavior and molecular mechanisms, and capturing cell-extracellular matrix (ECM) interactions. In this study, we present a novel 3D bioprinting system comprising a nanoinjector, finely crafted micropipette nozzles of ~100 µm diameter, and a micromanipulator. This system exhibited an impressive 80% accuracy in precisely depositing diseased fibroblast-laden droplets directly onto the alveolar spaces and airways of ex vivo precision-cut lung slices (PCLS). These PCLS were decellularized to obtain an ECM bioscaffold and combined with an aqueous two-phase system (ATPS) of dextran (DEX, MW:​ 500 kDa) and polyethylene glycol (PEG, MW:​ 35 kDa) for controlled and precise droplet deposition. Furthermore, ‘fibronectin’ was incorporated into the PEG-immersed PCLS to improve the adhesion of diseased lung fibroblasts (CAF) and normal lung fibroblasts (IMR-90). The use of decellularized PCLS, which closely mimics native tissue architecture (90%) and structural relevance (70%), was assessed for bioprinting and increased interaction, adhesion, expansion, and migration of the fibroblasts. The bioprinted cells were observed to expand, proliferate, and migrate onto the PCLS and showed significant 80% viability until Day 8. Drawing from the outcomes of this study, the nanoinjector bioprinting of fibroblasts on ex vivo decellularized ECM, coupled with fibrotic factors and growth factors, could potentially reduce the high costs of commercial 3D bioprinters and achieve pathological progression leading to a lung fibrosis model.