AbstractGreenhouse gas (GHG) emissions from freshwater streams are poorly quantified in sub-tropical climates, especially in the southern hemisphere where land use is rapidly changing. Here, we examined the distribution, potential drivers, and emissions of carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) from eleven Australian freshwater streams with varying catchment land uses yet similar hydrology, geomorphology, and climate. These sub-tropical streams were a source of CO₂ (74 ± 39 mmol m⁻² day⁻¹), CH₄ (0.04 ± 0.06 mmol m⁻² day⁻¹), and N₂O (4.01 ± 5.98 µmol m⁻² day⁻¹) to the atmosphere. CO₂ accounted for ~ 97% of all CO₂-equivalent emissions with CH₄ (~ 1.5%) and N₂O (~ 1.5%) playing a minor role. Episodic rainfall events drove changes in stream GHG due to the release of soil NO_x (nitrate + nitrite) and dissolved organic carbon (DOC). Groundwater discharge as traced by radon (²²²Rn, a natural groundwater tracer) was not an apparent source of CO₂ and CH₄, but was a source of N₂O in both agricultural and forest catchments. Land use played a subtle role on greenhouse gas dynamics. CO₂ and CH₄ increased with catchment forest cover during the wet period, while N₂O and CH₄ increased with agricultural catchment area during the dry period. Overall, this study showed how DOC and NO_x, land use, and rainfall events interact to drive spatial and temporal dynamics of GHG emissions in sub-tropical streams using multiple linear regression modelling. Increasing intensive agricultural land use will likely decrease regional CO₂ and CH₄ emissions, but increase N₂O.