Flexible　fiber　capacitors,　renowned　for　their　lightness,　softness,　and　bendability,　are　prime　candidates　for　wearable　electronic　devices.　However,　a　significant　challenge　for　their　practical　application　in　flexible　wearable　devices　lies　in　the　mismatch　between　the　electrochemical　and　mechanical　properties　of　their　fibrous　electrode　materials.　In　this　work,　a　thermoplastic　polyurethane　(TPU)　film　is　prepared　using　electrostatic　spinning　and　loaded　with　polyaniline　(PANI)　through　in　situ　polymerization.　By　twisting　the　PANI-TPU　fiber　film　a　certain　number　of　turns,　a　fiber　supercapacitor　capable　of　stabilizing　under　large　tensile　deformations　is　achieved.　This　PANI-TPU　fiber　demonstrates　a　remarkable　tensile　strain　tolerance　of　537.8%,　while　the　entire　supercapacitor　device　maintains　stable　and　high　specific　capacitance　characteristics　(＞45.12　F　cm−3)　even　under　large　tensile　strains.　Furthermore,　the　PANI-TPU　fiber　excels　not　only　in　energy　storage　but　also　in　sensing　performance,　enabling　the　monitoring　of　human　pulse　signals　and　movements　across　various　body　parts.　Leveraging　the　versatility　of　the　composite　fiber,　it　can　be　flexibly　integrated　into　a　self-supplied　integrated　sensing　system.　This　system　can　drive　the　PANI-TPU　fiber　sensors　to　identify　and　classify　different　movement　gestures　of　the　human　body　as　well　as　diverse　shapes　of　objects　grasped　by　manipulators.　©　2024　The　Royal　Society　of　Chemistry.