Inverted growth and the development of associated cell processing, are likely to offer a significant degree of freedom for improving the performance of many III‐V multijunction cascades and open new avenues for advanced multijunction concepts. This is especially true for the development of high‐efficiency Al0.37Ga0.63As/GaAs cascades where the high growth temperatures required for the AlGaAs top cell growth can cause the deterioration of the tunnel junction interconnect. In the approach of inverted‐grown AlGaAs/GaAs cascade cells, the AlGaAs top cell is grown first at 780 °C and the GaAs tunnel junction and bottom cell are grown at 675 °C. After the inverted growth, the AlGaAs/GaAs cascade structure is selectively removed from the parent substrate. The feasibility of inverted growth is demonstrated by a fully‐processed, inverted‐grown, thin film GaAs cell with a 1‐sun AM1.5 efficiency of 20.3%. Also, an inverted‐grown, thin‐film, Al0.34Ga0.66As/GaAs cascade with AM1.5 efficiencies of 19.9% and 21% at 1‐sun and 7‐suns, respectively, has been obtained.