The isotope shifts of the 2s2 1S0 to 2s2p 1P1 and 3P1 transitions in the four-electron beryllium atom are calculated by using the multi-configuration Dirac–Hartree–Fock method and the relativistic configuration interaction approach for the stable and short-lived beryllium isotopes. The results provided herein can be employed for the consistency check with the nuclear rms charge radii from the experimental isotope shifts by using the corresponding transitions for the short-lived nuclei 7,10−12Be and 14Be. The analogous isotope shift results could also be obtained for the beryllium-like ions by the methods used here.