Klose made 29 appearances as FC Thun won the 2009–10 Swiss Challenge League, scoring in a 4–0 home win over FC Gossau on 5 December. He made 30 appearances in the following season in the Super League, scoring three times. On 28 May 2011, he left Thun for 1. FC Nürnberg on a three-year deal for around €400,000. He made 13 league appearances from August to November, and then 8 from March to May with the reserves in the Regionalliga Bayern; he scored the only goal on 8 May against FC Ingolstadt 04 II. The following season he returned to the first team, and scored twice in 32 Bundesliga appearances.
VfL Wolfsburg
On 1 July 2013, Klose signed for VfL Wolfsburg on a four-year contract. He was sent off on his Wolfsburg debut, a 2–0 away defeat to rivals Hannover 96 on 10 August, and only played 9 more league games throughout the season, with just 4 more as a starter. However, he played the full 90 minutes as Wolfsburg won the DFB-Pokalfor the first time with a 3–1 victory over Borussia Dortmund on 30 May 2015.
Norwich City
On 18 January 2016, Klose signed for Premier League side Norwich City on a three-and-a-half-year contract for an undisclosed fee. He made his debut on 2 February in a 3–0 home loss to Tottenham Hotspur, and totalled ten games for the relegated Canaries, scoring to open a 3–2 win over Newcastle United at Carrow Road on 2 April. In 2018–19, Klose played 31 times as Norwich won the EFL Championship and scored four goals, including both of a 2–1 win at Nottingham Forest on 20 October 2018. He signed a new three-year contract on 20 May 2019, tying him to the club until 2022. Klose suffered a posterior cruciate ligament injury to his right knee on 27 August 2019, as Norwich were eliminated from the EFL Cup by Crawley Town. He did not return until the following 19 June, when he played a 3–0 home loss to Southampton following the COVID-19 hiatus. Eight days later, he was sent off for the first time for Norwich, when he pulled down Odion Ighalo in a 2–1 home extra-time loss to Manchester United in the sixth round of the FA Cup.
International career
He was named in the Team of the Tournament at the 2011 UEFA European Under-21 Championship in which his country reached the final. He also represented Switzerland at the 2012 Olympics, and played every match as Switzerland were eliminated in last place in Group B. He made his full international debut for Switzerland on 10 August 2011, replacing Philippe Senderos in the 57th minute of a 2–1 away friendly win against Liechtenstein. On 7 October he played his first competitive international and start, as Switzerland lost a Euro 2012 qualifier 2–0 away to Wales. He also played two matches in the team's successful 2014 FIFA World Cup qualification, but was not selected for the tournament. An injury sustained by Klose while playing for Norwich City in April 2016, ultimately led to him missing selection for Euro 2016.
