Theo Gries began playing football in Mittelbrunn at the 1 FC Mittelbrunn. From Mittelbrunn he moved to TuS Landstuhl. There he played in youth, - and amateur teams.
The midfielder Theo Gries began his professional career in 1983 at the former first division team 1 FC Kaiserslautern, where he, however, were held to a Bundesliga use. For the 1985/86 season he moved to Alemannia Aachen and played for the Aachen to October 1988 in League 2 125 games in which he scored 47 goals.
In the fall of 1988, the change to league rivals Hertha BSC followed. With the Hertha he rose in 1990 under its former Aachen coach Werner Fuchs in the first Bundesliga; but the Berlin already increased in the following season 1990/91 again. For Hertha he came to 176 inserts League with 74 Torerfolgen, including 28 games and 6 goals in the Bundesliga.
Even during the 1993/94 season moved the crowd to Hannover 96 After 20 games and 8 goals in the 2nd Bundesliga Theo Gries finished his career as a professional footballer at end of season 1994. He plays then for one season in the Regionalliga Nordost for Tennis Borussia Berlin and won the Berlin Cup. In the third- highest division Gries had met in 13 games once.
After his active career as a footballer, he worked as a coach for Tennis Borussia Berlin and Hertha Zehlendorf. He also served as head of the junior center from Alemannia Aachen. Since April 2008 he has directed the youth development center of the first FC Union Berlin and training since July 2008 also the second team of 1 FC Union Berlin. When that he was after disagreements with Uwe Neuhaus, coach of the first team, suspended. He remains the club but by 2013 as a scout.