This study investigates the preparation and stability of vanilla nano-emulsions, specifically focusing on the addition of cinnamon essential oil to improve stability. The nano-emulsions were prepared using a microfluidizer processor with sodium caseinate and Tween 80 as the aqueous phases. Transmission electron microscopy (TEM) images revealed that the nano-emulsions were spherical, with some flocs observed in the cinnamon-vanilla nano-emulsions (C/VM and C/VT). The average droplet sizes of C/VM and C/VT increased only by 14.99% and 15.01%, respectively, after heating at 100 °C for 20 minutes, and remained below 120 nm after 24 days of storage at 25 °C. The instability indices of C/VM and C/VT were reduced by 34.9% and 39.08%, respectively, compared to the cinnamon-only nano-emulsions (C, VM, and VT). Antioxidant activity tests showed no significant effect of the presence of flocs on the antioxidant capacity of the nano-emulsions. These findings indicate that the improved stability of the composite essential oil nano-emulsions can broaden their applications.This study investigates the preparation and stability of vanilla nano-emulsions, specifically focusing on the addition of cinnamon essential oil to improve stability. The nano-emulsions were prepared using a microfluidizer processor with sodium caseinate and Tween 80 as the aqueous phases. Transmission electron microscopy (TEM) images revealed that the nano-emulsions were spherical, with some flocs observed in the cinnamon-vanilla nano-emulsions (C/VM and C/VT). The average droplet sizes of C/VM and C/VT increased only by 14.99% and 15.01%, respectively, after heating at 100 °C for 20 minutes, and remained below 120 nm after 24 days of storage at 25 °C. The instability indices of C/VM and C/VT were reduced by 34.9% and 39.08%, respectively, compared to the cinnamon-only nano-emulsions (C, VM, and VT). Antioxidant activity tests showed no significant effect of the presence of flocs on the antioxidant capacity of the nano-emulsions. These findings indicate that the improved stability of the composite essential oil nano-emulsions can broaden their applications.