Incorporating antioxidants in functional foods represents an excellent dietary approach to prevent oxidative stress. The present work aimed to create a novel formulation of biscuits using a combination of Zingiber cassumunar (ZC) and purple sweet potato (PSP) as the main ingredients, in producing a functional food product that possesses antioxidant properties. The present work involved conducting trials and implementing optimisation techniques in order to obtain three distinct biscuit formulations, namely F1 (ZC 0.75 g: PSP 5.25 g), F2 (ZC 0.45 g: PSP 5.55 g), and F3 (ZC 0.28 g: PSP 5.72 g). The proximate analysis of the three formulations met the Standard Nasional Indonesia (SNI) criteria for biscuits, which encompassed parameters such as moisture content, ash, fat, protein, crude fibre, and metal residue. The F3 biscuits were chosen as the test biscuits in subsequent experiments due to their superior quality. The administration of F3 biscuits at a dosage of 1.94 g per 200 g of body weight to rats fed with high-fat diet for 28 d resulted in a substantial reduction (p < 0.05) in malondialdehyde levels, with a mean value of 2.17 ± 0.22 nmol/mL. Additionally, this intervention improved superoxide dismutase activity, with a mean value of 72.95 ± 3.06%. The F3 biscuits demonstrated promising antioxidant potential. This could serve as a basis for further clinical trials in humans before its potential commercialisation. Further investigation into the formulation of the biscuit is necessary, especially concerning the moisture, ash, and crude fibre levels present.