Abstract The study of relationships between traits is essential for understanding the behavior of variables of interest and advancing breeding programs. In popcorn ( Zea mays L. var. everta (Sturtev) L.H. Bailey), popping expansion (PE) is considered the primary quality trait, but knowledge about the impact of agronomic traits and Fusarium spp. infection, known to directly damage grain integrity, is still limited. Thus, this study aimed to investigate the impact of a set of agronomic traits and Fusarium severity on popcorn PE. Four trials were conducted in Campos dos Goytacazes, Rio de Janeiro, Brazil. A randomized block design with three replications was adopted, evaluating 127 S 7 popcorn lines and collecting data on 14 variables. In each trial, phenotypic and genotypic correlations were estimated, and path analysis was performed using PE as the dependent variable. Correlations between kernel width (KW) × 100‐grain weight (W100), number of leaves (NL) × number of leaves above the ear (NLAE), and grain yield (GY) × prolificacy (PR) were high and consistent. KW and severity of Fusarium ear rot (SFER) showed the strongest negative genetic correlations with PE (−0.48 to −0.66 and −0.50 to −0.71, respectively), with direct effects confirmed by path analysis. GY exhibited a positive direct effect on PE in most trials, while the low correlation between these variables was attributed to indirect effects. These findings highlight the potential of grain morphology and resistance to FER as selection criteria to improve PE and suggest possibilities for simultaneous gains through integrated selection strategies.