A charge designable and tunable green fluorescent protein (GFP)-based protein delivery strategy was proposed. The acquired His29GFP selectively permeates the cell membrane at a target pH of 6.5 and escapes from the endosome efficiently. The delivered RNase A caused substantial mRNA degradation in HeLa cells, and proliferation inhibition in different cell lines and a 3D tumor model at pH 6.5.