PKS 0301-243 is a distant (z=0.266) high-frequency-peaked BL Lac object, detected both at high and very high energies (VHE) with Fermi/LAT and H. E. S. S., and which experienced a flare in May 2010 in the GeV band. H. E. S. S. observations of PKS 0301-243 carried out between September 2009 and December 2011 result in a strong detection of VHE gamma-rays from the source with a significance of 9.8 standard deviations. Multi-wavelength observations from optical to GeV gamma-rays are also presented. The VHE spectrum is used to derive an upper limit on the opacity of the universe to gamma-rays.