Under the terms of the agreement, the German side will pay €400,000 for a year-long loan, while they will have the option to make the transfer permanent for additional €12.5 million.
Djuricic will thus become club’s third signing in the space of few days, with Gonzalo Jara and Stefanos Kapino joining the ranks as well.
The Serbian midfielder was on the radar of quite a few top sides when he swapped Heerenveen for Benfica last summer, but he was never given a real chance to impress at Estadio da Luz.
Djuricic went on to make just 11 league appearances last term, while featuring in six European matches for the Eagles.
This will be a perfect opportunity for the 22-year-old to kick-start his career and he is widely expected to command a regular starting berth at Mainz.