Current cancer treatments are not adequate to cure cancer disease, as most chemotherapeutic drugs do not differentiate between cancerous and non-cancerous cells; which lead to systemic toxicity and adverse effects. We have developed a promising approach to deliver a potential anti-cancer compound (curcumin) for lung cancer treatment through pulmonary delivery. Three different sizes of curcumin micellar nanoparticles (Cur-NPs) were fabricated and their cytotoxicity effects (proliferation, apoptosis, cell cycle progression) were evaluated against non-small-cell lung cancer, human lung carcinoma (A549) and human lung adenocarcinoma (Calu-3). The in vitro cytotoxicity assay showed that Cur-NPs were more effective to kill lung cancer cells compared to DMSO-solubilised raw curcumin. The potency of the anti-cancer killing activities was size-dependent. Both raw curcumin and Cur-NPs were not toxic to healthy lung cells (BEAS-2B). Smaller Cur-NPs accumulated within nucleus, membrane and cytoplasm. Cur-NPs also induced apoptosis and caused G2/M arrest in both A549 and Calu-3 cell lines. Compared to raw curcumin, Cur-NPs were more effective in suppressing the expression of the inflammatory marker, Interleukin-8 (IL8). The aerosol performance of Cur-NPs was characterized using the next generation impactor (NGI). All Cur-NPs showed promising aerosolization property with mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) ranging between 4.8–5.2 and 2.0–2.1, respectively. This study suggests that inhaled curcumin nanoparticles could potentially be used for lung cancer treatment with minimal side effects.