Early career Tremmel's previous clubs include
Bayern Munich and
1860 Munich, where he spent three years as a youth, before joining
SpVgg Unterhaching where he made his senior debut. Tremmel left
Bavaria in 2002 for spells at
Hannover 96 then
Hertha BSC, where he spent
2004–05 in the reserve side. He then joined
Energie Cottbus in 2006 on a two-year contract, announcing his intention to leave the club on 29 April 2010. On 7 May 2010, his transfer to Hertha for the upcoming season was confirmed, but the transfer failed and he signed for
Red Bull Salzburg instead on 20 May 2010. in 2011
Swansea City Tremmel joined
Swansea City on 30 August 2011 on a free transfer following their promotion to the
Premier League. Swansea manager
Brendan Rodgers had brought Tremmel to South Wales and signed him after his impressive pre-season performances against
Celtic and
Real Betis. Tremmel made his competitive debut for Swansea on 7 January 2012 in an
FA Cup fixture at
Barnsley, helping his team to a 2–4 away win. He made his Premier League debut on 26 February 2012 in a 2–0 away loss against
Stoke City at the
Britannia Stadium. Tremmel made his fourth appearance for Swansea, and his first in the
2012–13 season, in a 3–1 win against Barnsley in the
League Cup. Following an injury suffered by first choice goalkeeper
Michel Vorm on 27 October 2012, Tremmel started to have a run of games in the Swansea team for the first time. Swansea, now with Tremmel in the side, went on a seven-match unbeaten run that included memorable away wins at
Liverpool in the League Cup, and
Newcastle United and
Arsenal in the Premier League. He also managed to keep clean sheets against the likes of
Chelsea, Arsenal and Liverpool. These performances were met with praise from then-manager
Michael Laudrup, who said, "Gerhard has done well and it is very important to know you have a goalkeeper of quality when things happen." On 7 February 2013, Swansea announced that they had extended their contract with the Bavarian until the summer of 2015. On 24 February 2013, Tremmel helped Swansea beat
Bradford City 5–0 to win the
2012–13 League Cup by the competition's highest-ever winning margin for the final. This achievement landed Swansea's first major trophy as well as qualification for the
2013–14 UEFA Europa League. German mass tabloid
Bild hailed Tremmel's "career highlight" at the "legendary"
Wembley Stadium and a just reward for 15 years of hard work and professionalism in the game. On 28 May 2015, Tremmel confirmed that he would not be renewing his contract with Swansea and would therefore be released by the club. On 11 August, however, he re-joined the side, signing a two-year contract to keep him at the club until June 2017. On 22 May 2017, the club announced his release along with seven other players after he had only appeared in the
EFL Trophy during the 2016–17 season.
Werder Bremen Tremmel was loaned out to
Werder Bremen, in his native Germany, on 28 January 2016. ==Post-playing career==