Berger managed the youth team of the GDR. In 1979, he used a match in Yugoslavia to flee to West Germany. He signed with Second Bundesliga side SV Darmstadt 98. As a GDR refugee he suffered many threats by the East German secret police Stasi. He survived being poisoned whilst managing KSV Hessen Kassel in the mid-1980s. Evidence of the threats to his life were not available until 1990 when Germany was reunified, after which he was able to search his Stasi files.
He was renowned as a great motivator, helping clubs threatened with relegation, but with little chance to build up teams over a longer period. Berger became the ’’fireman’’ of the Bundesliga after he twice failed to gain promotion to the Bundesliga with KSV Hessen Kassel, ending up in fourth position in the Second division of the Bundesliga (1984 and 1985). His greatest achievements were two third positions with Eintracht Frankfurt in 1990 and with FC Schalke 04 in 1996. He was replaced as manager of Schalke by Huub Stevens in October 1996 shortly before they won the UEFA Cup in 1997.
Berger's last big success was reaching the DFB-Pokal final with Alemannia Aachen, a side from the Second division of the Bundesliga. However his contract was cancelled, by mutual agreement, after they lost to the then current champions (SV Werder Bremen) and failed to gain promotion to the Bundesliga.
Berger was the father of three children. In 2002 he had to interrupt his time as Alemannia Aachen manager due to an operation on an intestinal tumour. In 2005 he was operated on again, this time on livermetastasis. He released his biography "Meine zwei Halbzeiten: Ein Leben in Ost und West" (English: My Two Halves: A Life in the East and in the West) over the Leipzig based Rowohlt-Verlag in March 2009. Berger died on 23 June 2010 of an enterictumor.