During nearly ten professional seasons, Hermann played with SV Werder Bremen. He made his Bundesliga debut on 11 December 1982, in a 2–1 win at VfL Bochum, but it would be only his only appearance of the season, and he would also amass a single one in the following.
After a slow start, Hermann became a very important defensive member, often partnering legendary Miroslav Votava in central midfield. In the 1987–88 season, he played in 30 matches (receiving only one yellow card), as Werder won the national championship after 23 years. As his presence was diminishing he still appeared in six matches during the club's 1991–92 Cup Winners' Cup victorious campaign, although he did not play in the final.
Hermann recorded just two international caps for West Germany in his professional career, making his debut on 21 September 1988, in a friendly against the Soviet Union (1–0) in Düsseldorf.
His other appearance took place in the final test of the nation ahead of the 1990 FIFA World Cup, playing nine minutes in another 1–0 success, on 30 May, against Denmark. During the final stages, he was the only outfield player besides striker Frank Mill and defender Paul Steiner not to receive a single minute during the competition.
In December 1992, Hermann left Bremen for another first-divisioner, SG Wattenscheid 09 (in Bochum) helping the modest side retain its top level status in his one half season stint. He finished his career in the second division with Hannover 96, retiring at almost 36; he later had a go at managing in amateur football, mainly with VSK Osterholz-Scharmbeck.