We report a measurement of the half-life of the 136Xe two-neutrino double-β decay performed with a novel direct-background-subtraction technique. The analysis relies on the data collected with the NEXT-White detector operated with 136Xe-enriched and 136Xe-depleted xenon, as well as on the topology of double-electron tracks. With a fiducial mass of only 3.5 kg of Xe, a half-life of 2.34+0.80−0.46(stat)+0.30−0.17(sys)×1021yr is derived from the background-subtracted energy spectrum. The presented technique demonstrates the feasibility of unique background-model-independent neutrinoless double-β-decay searches.Received 25 November 2021Revised 25 January 2022Accepted 6 April 2022DOI:https://doi.org/10.1103/PhysRevC.105.055501©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDouble beta decayLifetimes & widthsNeutrinoless double beta decayNuclear structure & decaysRare decaysProperties90 ≤ A ≤ 149Nuclear PhysicsParticles & Fields