To improve the stability and bioavailability of ginger essential oil (GEO), the optimal ultrasonic power, Tween 80 addition amount, and GEO addition amount for preparing ginger essential oil-Tween 80 nanoemulsions (GEO-T80NE) were first screened via single-factor experiments and orthogonal experiments using particle size and encapsulation efficiency as indicators. Based on these findings, carboxymethyl chitosan (CMCS) was utilized as a composite emulsifier in an equal ratio to Tween 80 to prepare ginger essential oil composite nanoemulsions (GEOCNs). The results indicated that under 15 min of ultrasonic treatment, the optimal process parameters for GEO-T80NE preparation were an ultrasonic power of 320 W, 3% Tween 80, and 4% GEO. The resulting GEO-T80NE exhibited an average particle size of 268.00 ± 1.53 nm and an encapsulation efficiency of 88.50 ± 0.17%. When an equal proportion of CMCS was added, the prepared GEON-CMCS demonstrated an average particle size of 284.67 ± 0.58 nm. Furthermore, at 46 °C, the average particle size of GEOCNs was 48% smaller than that of GEO-T80NE, demonstrating effectively enhanced temperature stability. Additionally, the scavenging rates of GEOCNs against DPPH and ABTS free radicals increased by 17.47% and 9.94%, respectively. In conclusion, the combined application of CMCS and Tween 80 effectively improves the physical stability and functional properties of GEO-T80NE, offering a valuable reference for its application in the food, pharmaceutical, and other related industries.