In April 2007, he scored a goal helping his club break Skoda Xanthi's unbeaten home run in the Superleague Greece and secure a place in the Greek Cup final against Larissa.

After being mostly left out of the starting lineup in the beginning of 2008–09 season, he was included in the team in November and was voted "Man of the Match" in a 3–0 win in Germany against Werder Bremen in the UEFA Champions League, where he scored the third goal for Panathinaikos.

[2][3] Tziolis played a regular role in Bremen's midfield and helped the club to make the UEFA Cup final against Shaktar Donetsk, on 20 May 2009.

In August 2010, Tziolis moved to La Liga side Racing Santander on a one-year loan deal.

[6] After a successful league campaign in the second half of the season Racing Santander signed him permanently from Siena for an undisclosed fee.

[12] At the beginning of 2014–15 season, Tziolis returned to PAOK and played 34 games in all competitions scoring one goal for the Greek Cup.

On 27 November 2015, Tziolis in the UEFA Europa League match against Gabala FK achieved 400 appearances with all his clubs for all competitions.

In December 2015 the club stated it wanted to keep the international midfielder for many years and that Tziolis had a first meeting with technical director Frank Arnesen, to speak about the terms of a contract extension.

On 30 January 2017, Tziollis joined Scottish Premiership club, Heart of Midlothian on a six-month deal running to the end of the 2016–17 season.

On 4 August 2017, Tziolis signed a two-year contract with newly promoted Saudi Professional League club Al-Fayha FC.

After representing his country 13 times for the U21 side, Tziolis made his international debut for Greece on 21 January 2006 in a friendly match against South Korea.

He would be included in the team for two major events, but Greece coach Fernando Santos dropped Tziolis from his final 23-player squad for the UEFA Euro 2012.

Tziolis had a poor season and would not get a regular spot in the Monaco team, in Ligue 2, while his performance in the last friendlies did little to change Santos's mind.