This work aims to investigate the mechanisms governing H₂ jet flame evolution and stabilisation by precisely controlling the jet ignition location using a laser-induced plasma in compression-ignition engine-relevant conditions. The experiments examine the flame evolution with high-speed schlieren imaging and pressure trace measurements in an optically-accessible constant-volume combustion chamber over a range of ambient O₂ concentration (10–21 vol%) and temperature (600–800 K) conditions. Optical results reveal that in most cases, a localised flame kernel forms at the time and location of the laser-induced plasma and grows in connected regions to engulf the entire upstream and downstream jet volume of the ignition spot. The images also reveal that the flame lift-off is sensitive to ambient O₂ and temperature changes. The flame appears attached to the nozzle at 21 vol% O₂, but becomes lifted at a lower ambient O₂ concentration and a colder temperature. A simplified numerical analysis suggests that edge-flame deflagration into stratified premixed fuel-ambient reactant streams explains the lift-off response to ambient O₂ and temperature changes. Furthermore, at the lowest tested O₂ concentration, the flame stabilisation occurs in leaner mixtures at the jet peripheral where it is likely exposed to stronger turbulence-chemistry interactions.