The unprecedented advancement in power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) has rendered them a promising game‐changer in photovoltaics. However, unsatisfactory environmental stability and high manufacturing cost of window electrodes are bottlenecks impeding their commercialization. Here, a strategy is introduced to address these bottlenecks by replacing the costly indium tin oxide (ITO) window electrodes via a simple transfer technique with single‐walled carbon nanotubes (SWCNTs) films, which are made of earth‐abundant elements with superior chemical and environmental stability. The resultant devices exhibit PCEs of ≈19% on rigid substrates, which is the highest value reported to date for ITO‐free PSCs. The facile approach for SWCNTs also enables application in flexible PSCs (f‐PSCs), delivering a PCE of ≈18% with superior mechanical robustness over their ITO‐based counterparts due to the excellent mechanical properties of SWCNTs. The SWCNT‐based PSCs also deliver satisfactory performances on large‐area (1 cm2 active area in this work). Furthermore, these SWCNT‐based PSCs can retain over 80% of original PCEs after exposure to air over 700 h while ITO‐based devices only sustain ≈60% of initial PCEs. This work paves a promising way to accelerate the commercialization of ITO‐free PSCs with reduced material cost and prolonged lifetimes.

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