The purpose of this research was to enhance the transdermal delivery of diclofenac sodium niosomal formulations. To characterise the obtained niosomes, SEM, XRPD, DSC and ATR-FTIR were employed. The size of the niosomes increased from 158.00 ± 6.17 to 400.87 ± 4.99 nm when cholesterol was incorporated into the formulations. It was observed that the zeta potential of niofenac varies from −25.40 ± 1.352 to −43.13 ± 1.171 mV when the cholesterol percentage decreased from 2% to 0.2%. The higher entrapment efficiency percentage (63.70 ± 0.18%) was obtained for the formulations with larger particle sizes and higher cholesterol content. The optimised niofenac formulation showed a controlled release fashion where 61.71 ± 0.59% of the drug released within 24 h. The results showed that the value of permeated diclofenac sodium through the skin layers was higher for the niofenac gel formulation (242.3 ± 31.11 µg/cm2) compared to simple gel formulation (127.40 ± 27.80 µg/cm2). Besides, niofenac formulation outperformed the anti-inflammatory activities in the formalin test compared to the control and diclofenac simple gel group. The licking time was significantly lower in both early (40.2 ± 7.3 s) and late stages (432.4 ± 31.7 s) for niofenac compared to conventional formulation (early stage 130.4 ± 8.73 s and late stage 660.6 ± 123.73 s). This study indicates that niosomal formulations can improve drug therapeutic effects by increasing drug delivery to specific sites.