Selected volatile organic compounds (VOCs), such as benzene (C₆H₆), cyclohexane (C₆H₁₂), isoprene (C₅H₈), cyclopropanone (C₃H₄O), propanol (C₃H₈O), and butyraldehyde butanal (C₄H₈O), in exhaled human breath can act as indicators or biomarkers of lung cancer diseases. Detection of such VOCs with low density would pave the way for an early diagnosis of the disease and thus early treatment and cure. In the present investigation, the density-functional theory (DFT) is applied to study the detection of the mentioned VOCs on Ti₃C₂T_X MXenes, saturated with the functional groups T_x = O, F, S, and OH. For selectivity, comparative sensing of other interfering air molecules from exhaled breath, such as O₂, N₂, CO₂, and H₂O is further undertaken. Three functionalization (T_x = O, F, and S) are found promising for the selective detection of the studied VOCs, in particular Ti₃C₂O₂ MXenes has shown distinct sensor response toward the C₅H₈, C₆H₆, C₆H₁₂, and C₃H₄O. The relatively strong physisorption ( $${E}_{ads}\cong -0.45 to-0.65 {\text{eV}}$$E ads ≅ - 0.45 t o - 0.65 eV ), triggered between VOC and MXene due to an enhancement of van der Waals interaction, is found responsible to affect the near Fermi level states, which in turn controls the conductivity and consequently the sensor response. Meanwhile, such intermediate-strength interactions remain moderate to yield small desorption recovery time (of order $$\tau \cong \mu {\text{s}}-{\text{ms}})$$τ ≅ μ s - ms ) using visible light at room temperature. Thus, Ti₃C₂O₂ MXenes are found promising candidate material for reusable biosensor for the early diagnosis of lung cancer diseases through the VOC detection in exhaled breath.