Starting from the purely microscopic model, we go beyond conventional mean-field theory and develop a self-consistent microscopic thermodynamic framework for disordered 2D superconductors. It incorporates the fermionic Bogoliubov quasiparticles, bosonic Nambu-Goldstone (NG) quantum and thermal phase fluctuations in the presence of long-range Coulomb interactions, and topological Berezinskii-Kosterlitz-Thouless (BKT) vortex-antivortex fluctuations on an equal footing, to self-consistently treat the superconducting gap and superfluid density. This unified phase-fluctuating description naturally recovers the previously known limiting results: the superconducting gap in the 2D limit can remain robust against long-wavelength NG phase fluctuations at $T=0^{+}$ due to Coulomb-induced regularization, while the gradual proliferation of BKT fluctuations as the system approaches criticality drives a separation between the global superconducting transition temperature $T_c$ and the gap-closing temperature $T^{*}$. In contrast to mean-field theory, which predicts 2D superconductivity to be independent of carrier density and nonmagnetic disorder (Anderson theorem), the incorporation of phase fluctuations generates a density- and disorder-dependent zero-point gap $\mathrm{\Delta }\left(0\right)$ and consequently $T_c$ and $T^{*}$. Remarkably, applications to bilayer ${\mathrm{MoS}}_2$ [Nat. Nanotechnol. 14, 1123 (2019)] and disordered ${\mathrm{InO}}_x$ thin films [Nat. Phys. 21, 104 (2025)] quantitatively reproduce key experimental observations in excellent agreement. The framework offers a useful theoretical tool for understanding phase-fluctuation-dominated superconductivity.

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• BKT transition
• Phasons
• Superconducting fluctuations
• Superconducting phase transition
• Superconductivity
• Thin films
• Many-body techniques
• Methods in superconductivity
• Renormalization group