With　the　continuous　advancement　of　electronic　devices,　flexible　thin　films　with　both　thermal　management　functions　and　excellent　electromagnetic　interference　(EMI)　shielding　properties　have　received　much　attention.　Hence,　inspired　by　Janus,　a　CNF/MXene/ZnFe2O4　@PANI　composite　film　with　an　asymmetric　gradient　alternating　structure　was　successfully　prepared　by　adjusting　the　filler　content　of　the　conductive　and　magnetic　layers　using　a　vacuum-assisted　filtration　method.　Benefiting　from　the　magnetic　resonance　and　hysteresis　loss　of　ZnFe2O4　@PANI,　conductive　loss　and　dipole　polarization　of　MXene,　as　well　as　the　exclusive　＂absorption-reflection-reabsorption＂　shielding　feature　in　the　alternating　multilayered　films,　CM&CZFP-4　G　film　has　superior　EMI　shielding　performance,　with　an　EMI　SE　of　up　to　45.75　dB　and　shielding　effectiveness　of　99.99　%.　Surprisingly,　the　composite　film　maintains　reliable　EMI　shielding　properties　even　after　prolonged　erosion　in　harsh　environments　such　as　high/low　temperatures,　high　humidity,　acids　and　alkalis.　Furthermore,　the　CM&CZFP-4　G　responded　quickly　within　about　50　s　and　reached　a　maximum　steady-state　temperature　of　235.8　degrees　C　at　an　applied　voltage　of　9.0　V,　indicating　the　obtained　film　acquired　outstanding　and　controllable　Joule　heating　performance.　This　result　was　attributed　to　the　homogeneous　dispersion　of　MXene　to　build　up　a　conductive　network　and　endow　the　CNF/MXene　with　high　conductivity.　Meanwhile,　the　fire　resistance　of　CM&CZFP-4　G　was　significantly　improved　compared　to　pure　CNF,　which　guaranteed　fire　safety　during　its　application.　Additionally,　contributed　by　long　fiber　entanglement　of　CNF,　extensive　hydrogen-bonding　interactions　and　multilayer　structural　design,　the　CM&CZFP-4　G　film　exhibits　excellent　mechanical　characteristics,　with　the　tensile　strength　and　fracture　strain　of　27.74　MPa　and　6.21　%,　separately.　This　work　offers　a　creative　avenue　to　prepare　multifunctional　composite　films　with　electromagnetic　shielding　and　Joule　heating　for　various　application　environments.　(c)　2025　Published　by　Elsevier　Ltd　on　behalf　of　The　editorial　office　of　Journal　of　Materials　Science　&　Technology.