Born in
Thessaloniki, Vosniadis had a three-year tenure at local third division side
Anagennisi Epanomi early into his managerial career, and he would lead Epanomi to promotion in the
2010/11 season, returning the club to the second division after a 29-year absence. From Epanomi, Vosniadis moved to
Apollon Smyrnis with immediate success, winning promotion to Super League 1 in the
2012/13 season. In January 2014, Vosniadis took on
Niki Volos 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. 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. He would later return to the club in the middle of the 2017/18 Super League 1 season, earning 15 points from 16 league matches. From 2018/19 through 2022/23, Vosniadis worked for
Chania, Niki Volos, and Apollon in the second division, earning 52 wins and 33 draws from 116 league matches, equaling 1.63 points per match. In July 2023, Vosniadis was appointed as manager of
Athens Kallithea, eventually leading the team back to the first division for the first time in 18 years. In June 2024, AKFC announced that Vosniadis would not return for the following season, but thanked him for his "outstanding work." For the 2024/2025 Super League season, Vosniadis coached
AEL and helped them reach promotion by winning the championship for group A. After the season AEL decided to move on and Vosniadis was hired by
Kalamata for the 2025/2026 season and he promoted the team in the first division after 25 years ==Managerial statistics==