The 1990–91 season was FC Dinamo București's 42nd season in Divizia A. It is the first season started after the Romanian Revolution, event that opened the borders. Because of this, Dinamo lost almost an entire team, and also his coach, Mircea Lucescu, all of them starting their careers abroad. That's why Dinamo started to build another team and ended this season without silverware. In the championship, the team finished third, seven points behind champions Universitatea Craiova. The same team from Oltenia ended the dream for Dinamo in the Romanian Cup.
In the European Cup, Dinamo began with the elimination of Irish team St Patrick's Athletic Dublin (4-0 and 1-1). Dinamo was eliminated in the second round by FC Porto.