The oral administration of celecoxib (CLX) is a real problem because of its low aqueous solubility that results in high variability in absorption and its severe adverse effect such as cardiotoxic effects and gastrointestinal toxicity. Self-nanoemulsifying drug delivery systems (SNEDDS) can enhance the poor dissolution and erratic absorption of poorly water-soluble drugs such as CLX. This study was conducted to investigate the potential of SNEDDS to enhance the efficacy of CLX on inflamed mucous tissue and reduce systemic adverse effects by increasing its poor dissolution properties. A pseudo-ternary phase diagram was derived from the results of CLX solubility experiments in various excipients. These studies revealed the use of Labrafil M 2515 CS as oil, tween 80 as a surfactant, and polyethylene glycol 400 as a co-surfactant for the optimization of SNEDDS formulations. Eight formulations were formulated and characterized by their particle size, polydispersity index, viscosity, globular shape, drug solubility, self-emulsification efficiency, in vitro drug release, and permeation. The anti-inflammatory effect of CLX-SNEDDS was evaluated by carrageenan-induced cheek oedema in rats. The cheeks were treated with CLX-SNEDDS before oedema induction and then noticed for narrow periods (2 h) followed by histopathological studies to determine the efficacy of treatment. The selected formulations (F3 and F5) showed spherical morphologies under transmission electron microscopy, mean droplet sizes of 116.9 ± 1.78 and 124 ± 1.87 nm, respectively, complete in vitro drug release, and high cumulative amounts of drug permeation in 8 h. They also showed significant remarkable cheek oedema inhibition in comparison with the control groups (p < 0.05). CLX-SNEDDS was found to achieve effective local therapeutic concentration and intended to reduce cheek oedema, congestive capillary, inflammatory cells, and side effects due to lower dose size.