The objective of this work is to obtain bright green and tunable emission by dopant engineering. It has been achieved in zinc gallogermanate (ZGG) nanodiscs by utilizing Mn²⁺and Cr³⁺ions as dopant and codopant, respectively. Based on photoluminescence measurement, we have found that the Cr³⁺ codopant triggers bright green emission of Mn²⁺ dopant in the nanodiscs by acting as a bridge to efficiently transfer the emission from the ZGG host to Mn²⁺ion. We have validated the efficacy of energy transfer by concentration dependent photoluminescence and lifetime measurement. There are only a few reports on green emitting bulk Mn²⁺ doped ZGG. This work highlights the strategy of chromium co-doping in enhancing its green emission as a nanostructure, which could be extended to other hosts.