Versatile ZnO nanowires with controlled dimensions and high surface-to-volume ratio were deposited on glass using aqueous solution growth, a simple, environmental-friendly and inexpensive method at 95°C. The effect of pure ZnO and aluminium doped ZnO (AlyZn1−yO, y=0.01, 0.03, 0.05) seed layers on glass substrates was thoroughly studied against the geometrical features of the as-grown ZnO nanowires. It is revealed that the Al-doped ZnO seed layers possess significantly smaller grain size than the undoped ones (y=0), while as the Al concentration increases up to y=0.05 their grain size minimizes down to 19±1.5nm for a thickness of 120nm. The ZnO nanowires’ diameter ranges from 20 to 40nm following the grain size of the AlyZn1−yO seed layer used, while their length is mainly affected from growth time and varies from 175±25nm to 750±150nm. It is demonstrated that ZnO nanowires’ arrays grown on glass substrates, pre-coated with Al-doped ZnO seed layers, show superior photocatalytic activity, leading to a prospective photocatalyst, especially for indoors applications.