We propose a simple and dry technique to functionalize and dope single-walled carbon nanotubes (SWCNTs) with ozone. The doping under ozone-controlled conditions (300 mg/h) during 30 min was shown to give a 4-fold decrease in the sheet resistance of SWCNT films (148 ω/square at the transmittance of 90%). Further ozone treatment of the SWCNTs leads to deterioration in the film conductance. The conductivity alteration is discussed in the light of the Criegee mechanism, oxidation and charge transfer during the ozone exposure. The samples were characterized by TEM, FT-IR, Raman, UV-vis-NIR, and XPS to confirm the findings of the work. The ozone-treated samples show increased hydrophilicity with increasing ozone treatment time, which makes possible to coat the SWCNT samples with inorganic materials. SWCNTs after ozone treatment can be successfully and uniformly coated by ZnO with the help of atomic layer deposition (ALD) technique.