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Abstract We report dissolution Dynamic Nuclear Polarization (d‐DNP) of [¹⁵N₃]metronidazole ([¹⁵N₃]MNZ) for the first time. Metronidazole is a clinically approved antibiotic, which can be potentially employed as a hypoxia‐sensing molecular probe using¹⁵N hyperpolarized (HP) nucleus. The DNP process is very efficient for [¹⁵N₃]MNZ with an exponential build‐up constant of 13.8 min using trityl radical. After dissolution and sample transfer to a nearby 4.7 T Magnetic Resonance Imaging scanner, HP [¹⁵N₃]MNZ lasted remarkably long with T₁values up to 343 s and¹⁵N polarizations up to 6.4 %. A time series of HP [¹⁵N₃]MNZ images was acquired in vitro using a steady state free precession sequence on the¹⁵NO₂peak. The signal lasted over 13 min with notably long T₂of 20.5 s. HP [¹⁵N₃]MNZ was injected in the tail vein of a healthy rat, and dynamic spectroscopy was performed over the rat brain. The in vivo HP¹⁵N signals persisted over 70 s, demonstrating an unprecedented opportunity for in vivo studies.