The mixed‐valent, europium borate Eu5(BO3)4 was synthesized from Eu2B2O5 and EuB2O4. Its structure was refined by Rietveld analysis. Eu5(BO3)4 crystallizes in space group Pnma (a=2229.77(2) pm, b=1599.91(2) pm, and c=877.75(1) pm) and was found to be isostructural with Eu5(BO2.51N0.49)4. Powder reflectance spectra (UV/vis/NIR) and magnetic susceptibility data of Eu5(BO3)4 and of the reference compounds EuIIB4O7 and EuIIIBO3 were measured. The spectrum of the mixed‐valent europium(II, III) borate shows the 7F0→7F6 transition of the Eu3+ ion and the intervalence charge transfer Eu2+→Eu3+. The experimental Bohr magneton number of Eu5(BO3)4, μobs/μB=14.90, agrees well to μcalc/μB for a combination of three Eu2+ and two Eu3+ per formula.