<p>Cytokinins (CKs) are key factors in modulating the growth and development of peanut pods during the rapid-expansion stage, which determines the final pod size. To explore the effect of exogenous CKs on pod development, two peanut varieties with contrasting pod sizes were used for the comparison of differences in the phenotype, cell number, endogenous CK level, and CK-related gene expression of pods under different concentrations of 6-benzyladenine (6-BA) treatment. Developing peanut pods were sampled at 10, 15, 20, 25, and 30&#xa0;days after pegging (DAP). The results indicated that the 6-BA treatment increased pod length and width and promoted dry matter accumulation, with 20&#xa0;mg L⁻¹ 6-BA generally having the most significant effect. Cytological analysis confirmed that 6-BA increased pod size by increasing the cell number during the rapid-expansion stage. Additionally, 6-BA treatment enhanced the expression of CK biosynthesis-related genes (<i>AhIPT1</i> and <i>AhIPT2</i>), resulting in elevated endogenous CK content. Furthermore, the upregulation of CK signal transduction-related genes (<i>AhHRS</i>) coincided with the increase in cell number, suggesting potential involvement in cell proliferation regulation. This coordinated response enhanced the maximum growth rate (<i>V</i>_max), earlier initiation of the rapid-expansion stage, and ultimately increased the pod size.</p>