[3] He made his Bundesliga debut on 24 September 1994 in a 5–0 home win against VfB Stuttgart, and finished his first season with 14 games and one goal.

Injuries and loss of form led to an eventual demotion to the Borussia Dortmund II where he played 24 league matches from 1998 to 2000.

[8][9] In January 2001, Tanko joined SC Freiburg, scoring in his fourth game to help to a 3–1 success at VfL Bochum, but also missed a great part of the following campaign due to a severe knee injury,[10] as the Black Forest team dropped down to the 2.

[citation needed] Tanko earned nine caps for Ghana, the last coming on 10 October 2004 – after an absence of eight years – in a 2006 FIFA World Cup qualifier against the Democratic Republic of Congo.

[1][16] In January 2020, Tanko was appointed as the head coach of the Ghana A' national football team, the local Black Stars.

[18] On Tuesday, 28 June 2022, Tanko was appointed the Head coach of the Black Meteors by the Executive Council of the Ghana Football Association.