[1][2] Vosniadis has won promotion to Super League 1, Greece's top division, on four occasions with Apollon Smyrnis, Niki Volou, Kerkyra, and Athens Kallithea.
[4] In January 2014, Vosniadis took on Niki Volou midseason, and would help steer them to a second place finish in the 2013/14 season and promotion to Super League 1, bringing the club back to the top flight for the first time in 48 years.
[5] Vosniadis would return to Apollon midway through the 2014/15 season with the club in the second division, narrowly missing out on promotion while making a run to the semi-finals of the 2014/15 Greek Cup where they were eliminated by Olympiacos.
In the 2015/16 season, Vosniadis would achieve his third promotion to the top division, this time with island side Kerkyra, finishing second in the table and edging out his former club Apollon.
In July 2023, Vosniadis was appointed as manager of Athens Kallithea,[6] eventually leading the team back to the first division for the first time in 18 years.