The corruption trial of Gojek co-founder and former Indonesian Education Minister Nadiem Makarim, with prosecutors seeking an 18-year sentence, is causing concern among Indonesians working overseas who saw him as a symbol of success and modernization.

For many Indonesians who have built careers abroad, Nadiem Makarim once represented a particular kind of homecoming success story. The Brown and Harvard University-educated co-founder of Gojek had walked away from the start-up world to serve in government, bringing with him the aura of Indonesia’s technology boom and the promise that private-sector talent could help modernise the state. Now, with prosecutors seeking an 18-year prison sentence for the former education minister in a corruption...