To determine the role of maize plants and their interaction with nitrogen (N) fertilizer in regulating subsoil methane (CH₄) fluxes, we conducted a two-year field experiment on a semiarid farm in northwestern China. Four treatments were evaluated: unplanted soil without (C0) or with (CN) N fertilization and planted maize without (P0) or with (PN) N fertilization. Soil surface fluxes and profile dynamics of CH₄ at depths of 0–50 cm in situ were monitored. The CH₄ concentrations decreased with increasing soil depth. Seasonal and vertical variations in CH₄ diffusive fluxes varied with maize phenology. The CH₄ fluxes in the 0–20 cm layers accounted for 48.9–57.5% of the total fluxes in the 0–50 cm layers. The surface CH₄ uptake was positively correlated with soil temperature during the fallow season and negatively correlated with soil water-filled pore space (WFPS) and exchangeable NH₄⁺ concentration during the growing season. Compared with the unplanted treatments, the presence of maize plants significantly decreased soil WFPS and increased surface CH₄ uptake during the growing season. The two-year mean cumulative diffusive CH₄ fluxes were also significantly increased by 33.1–36.3% at depths of 10–30 cm and by 15.8–66.4% at depths of 10–40 cm in the P0 and PN treatments, respectively. Compared with the P0 treatment, the PN treatment significantly increased the surface CH₄ uptake and cumulative CH₄ uptake at depths of 0–40 cm in 2015. There was no significant difference in the CH₄ surface and subsoil fluxes between the C0 and CN treatments. Our results suggested that N fertilization stimulated CH₄ diffusion and uptake mainly by promoting maize growth and subsequently the soil water consumption on a dryland farm.