Objective To investigate the intervention effect of group cognitive behavioral nursing in children undergoing chemotherapy for leukemia. Methods A total of 86 children undergoing chemotherapy for leukemia in Zhumadian Central Hospital from August 2022 to August 2024 were selected for a prospective study. They were divided into a control group (43 cases) and an observation group (43 cases) by the random number table method. In the control group, there were 23 boys and 20 girls; the age ranged from 7 to 14 years old [with an average of (10.56±1.13) years old]; the disease duration was from 1 to 3 years [with an average of (2.19±0.33) years]. In the observation group, there were 22 boys and 21 girls; the age ranged from 7 to 14 years old [with an average of (10.59±1.14) years old]; the disease duration was from 1 to 3 years [with an average of (2.16±0.35) years]. The control group received routine nursing, while the observation group received group cognitive behavioral nursing. Both groups received continuous nursing for 6 weeks. The mental state, coping style, quality of life, and family satisfaction were compared between the two groups. Statistical analysis was conducted using the t test and χ2 test. Results After nursing, the scores of separation anxiety, generalized anxiety, social phobia, school phobia, and somatization/panic of the Screen for Child Anxiety Related Emotional Disorders (SCARED) in the observation group were (5.54±1.01) points, (7.37±1.04) points, (4.39±1.05) points, (2.18±0.34) points, and (11.87±1.26) points, which were all lower than those in the control group [(8.76±1.07) points, (10.19±1.12) points, (6.08±1.10) points, (4.27±0.50) points, and (15.35±1.64) points] (t=14.350, 12.099, 7.288, 22.666, and 11.034, all P<0.001). After nursing, the score of facing situations of the Medical Coping Modes Questionnaire (MCMQ) in the observation group was (17.96±1.94) points, which was higher than that in the control group [(14.79±1.78) points]; the scores of avoidance and submission in the observation group were (10.01±1.05) points and (8.71±1.04) points, which were lower than those in the control group [(12.39±1.08) points and (11.53±1.07) points] (t=7.895 10.361, and 12.393, all P<0.001). After nursing, the scores of emotional function, social function, role function, and physical function of the Pediatric Quality of Life Inventory Version 4.0 (PedsQL4.0) in the observation group were (79.19±4.16) points, (82.29±4.70) points, (84.49±5.31) points, and (85.15±4.53) points, which were all higher than those in the control group [(72.28±4.04) points, (75.53±4.61) points, (76.06±5.23) points, and (77.19±4.26) points] (t=7.814, 6.733, 7.417, and 8.394, all P<0.001). The satisfaction rate of family members towards the nursing services in the observation group was 95.35% (41/43), which was higher than that in the control group [81.40% (35/43)] (χ2=4.074, P=0.044). Conclusion Group cognitive behavioral nursing can alleviate the negative psychological state in children undergoing chemotherapy for leukemia, improve their coping style, improve their quality of life, and enhance the satisfaction of family members with nursing services.