Higgsinos with masses near the electroweak scale can solve the hierarchy problem and provide a dark matter candidate, while detecting them at the LHC remains challenging if their mass splitting is <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi mathvariant="script">O</a:mi><a:mo stretchy="false">(</a:mo><a:mn>1</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>GeV</a:mi><a:mo stretchy="false">)</a:mo></a:mrow></a:math>. This Letter presents a novel search for nearly mass-degenerate Higgsinos in events with an energetic jet, missing transverse momentum, and a low-momentum track with a significant transverse impact parameter using <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mn>140</f:mn><f:mtext> </f:mtext><f:mtext> </f:mtext><f:msup><f:mi>fb</f:mi><f:mrow><f:mo>−</f:mo><f:mn>1</f:mn></f:mrow></f:msup></f:math> of proton-proton collision data at <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mrow><h:msqrt><h:mrow><h:mi>s</h:mi></h:mrow></h:msqrt><h:mo>=</h:mo><h:mn>13</h:mn><h:mtext> </h:mtext><h:mtext> </h:mtext><h:mi>TeV</h:mi></h:mrow></h:math> collected by the ATLAS experiment. For the first time since LEP, a range of mass splittings between the lightest charged and neutral Higgsinos from 0.3 to 0.9 GeV is excluded at 95% confidence level, with a maximum reach of approximately 170 GeV in the Higgsino mass. © 2024 CERN, for the ATLAS Collaboration 2024 CERN