Andreas Mayer played in the youth for the SV and FC Augsburg Röfingen before joining for 50,000 DM to Bayern Munich in 1991. Mayer was used in the second team of the championship record, got the second year a professional contract, but remained without Bundesliga game and moved in 1993 to FC St. Pauli in the Bundesliga 2, for whom he scored twice in 37 games. His professional debut was (9th Round ) on September 25, 1993 at 1:4 - defeat in the away game against Hannover 96 when he came on in the 40th minute for Joachim Philipkowski. His first goal he scored on 25 April 1994 ( 30th Round ) in a 2-1 victory in the home match against TSV 1860 Munich.
However, after the ascent to the 1995/96 season remained Mayer without Erstligaeinsatz, after which he joined at the beginning of the Norwegian game in 1996 for first division Stabæk IF and during the following season for Premier League rivals Rosenborg Trondheim. His last two years of playing for Rosenborg Trondheim he crowned with the two-time winning the championship, then played three years in Scotland, the Aberdeen FC in 2001 and returned back to Germany. It was followed by two seasons at Oberliga KSV Hessen Kassel before it drove him back to Northern Germany: FC St. Pauli and SV Wilhelmshaven and VfB Oldenburg were his other stations. After just one season at the Hessian division club VfB Association Süsterfeld he moved in January 2010 to the Lower Saxon Oberliga SV Meppen and signed a contract until the end of the season there. For the 2010/11 season he became player-coach for the football section of the SV Reinstetten that its games fought out in the Season IV of Württemberg league. From October 2012 to August 2013, he coached the Bavarian district division club TSV Burgau, for which he occasionally played. After 24 league games, he moved during the current 2013/14 season for county division ( Kreisklasse Allgäu) TV Gronenbach.
- Norwegian champion in 1997, 1998
- DFB Junior Club Cup winners 1991
- A young German champions Bayern selection