The midfielder featured throughout as Bucurest edged ACS Poli Timisoara 2-0 at the fully packed Arena Nationala stadium.
Mahlangu has made a dramatic turnaround from being a bench warmer to a regular starter.
The Secunda-born midfielder made 27 appearances this term despite early struggles with breaking into the team.
Slovakia intranational Adam Nemec netted a first-half brace for Dinamovistii.
This was the 28-year-old’s first piece of silverware since last winning the Allsvenskan, Svenska Cupen and Super Cup whilst still in the books of Helsingborgs IF in Sweden.
With newly elected Bafana coach Stuart Baxter expected to name his first squad ahead of the opening 2019 Africa Cup of Nations qualifier against Nigeria next month, the former Konyaspor midfielder’s name is amongst those who are expected to make a return to the national team roster, particularly in light of his recent impressive form.
Mahlangu has been capped 19 times by Bafana and has two goals to his name.