AbstractNitrous oxide (N₂O) is the third most important anthropogenic greenhouse gas and a major ozone‐depleting substance. Its main sources include anthropogenic activities (mostly agriculture) and natural emissions from ocean and soils. However, emission estimates for individual sources are highly variable due to uncertainties in N₂O lifetime estimates and partitioning among sources. We derive annual global N₂O emissions for 1990–2019 using NOAA Global Monitoring Laboratory (GML) surface N₂O observations and the N₂O lifetime calculated in the NASA GEOS‐5 chemistry climate model. The inferred global mean N₂O emissions has gradually increased from ∼15.8 TgN/yr in the early 1990s to ∼17.8 TgN/yr in the 2010s. This implies that anthropogenic N₂O emissions have grown rapidly from ∼6.7 TgN/yr in the 1990s to about ∼8.7 TgN/yr in the 2010s, a ∼30% increase. With specially designed N₂O isotopic tracers in 3‐D GEOSCCM, we estimate that, on global average, stratospheric enrichment contributes about +7.7‰/yr, +7.6‰/yr, +8.0‰/yr to tropospheric δ¹⁵N^α, δ¹⁵N^β, and δ¹⁸O budget, respectively. To balance the global mean isotopic signature for pre‐industrial terrestrial sources of δ¹⁵N^α ∼ 6.7‰, δ¹⁵N^β ∼ −12.6‰, δ¹⁸O ∼ 35.4‰, our 3‐dimensional isotopic budget simulation using the GEOSCCM suggests global mean anthropogenic isotopic signatures in the recent decades are δ¹⁵N^α ∼ −18‰, δ¹⁵N^β ∼ −20‰, δ¹⁸O ∼ 19‰. These anthropogenic isotopic estimates are significantly lighter than results from one‐box atmospheric model‐based estimates with the largest difference seen for δ¹⁵N^β. More surface isotopic measurements are needed to better quantify the N₂O isotopic signatures.