Sterilization of the culture medium using ultraviolet (UV)‐C reduces the potential adverse effects of microorganisms and allows for long‐term use. In the present study, we investigated the effects of a medium directly irradiated with UV‐C prior to in vitro culture on the development and quality of porcine in vitro‐fertilized embryos and the free amino acid composition of the culture media. The culture media (porcine zygote medium [PZM‐5] and porcine blastocyst medium [PBM]) were irradiated with UV‐C at 228 and 260 nm for 1 and 3 days, respectively. Next, the culture media were irradiated with UV‐C at 228 nm for 3, 7, or 14 days. After in vitro fertilization, the embryos were cultured in the UV‐C‐irradiated media for 7 days. Free amino acid levels in culture media irradiated with 228 and 260 nm UV‐C for 3 days were analysed. The blastocyst formation rate of embryos cultured in media irradiated with 260 nm UV‐C for 3 days was significantly lower than that of embryos cultured in non‐irradiated control media. However, 228 nm UV‐C irradiation for up to 14 days did not affect blastocyst formation rates and quality in the resulting blastocysts. Moreover, 260 nm UV‐C irradiation significantly increased the taurine concentration in both culture media and decreased methionine concentration in the PBM. In conclusion, UV‐C irradiation at 228 nm before in vitro culture had no detrimental effects on embryonic development. However, 260 nm UV‐C irradiation decreased embryo development and altered the composition of free amino acids in the medium.