[14] Klose developed his footballing skill and passion with local club SG Blaubach-Diedelkopf, which at the time was in the West-German seventh division.

[15][16] In 1998, Klose's professional career began at age 20 with a switch to the reserves at former Bundesliga outfit FC Homburg.

[20][21] He made his league debut on 6 August 2004 as a substitute for Paraguayan striker Nelson Valdez in a 1–0 home win against Schalke 04.

[26] On 26 June 2007, Bayern Munich club president Karl-Heinz Rummenigge confirmed his team had reached an agreement with Werder Bremen regarding the transfer of Klose.

[28] On 7 June 2011, with his contract about to expire, Klose did not reach an agreement with Bayern, thus leaving the club at the end of the 2010–11 season.

However, the occasion was tainted by a small section of radical Lazio fans holding a sign adapted from a motto used by the Nazis.

[39] On 2 December, Klose scored his ninth goal of the season, securing a 2–1 victory over Parma, lifting Lazio into fourth place in Serie A.

[44] Klose started the season by playing in the 2013 Supercoppa Italiana against Juventus, which ended in a 4–0 loss at the Stadio Olimpico.

This request was declined by Klose, who said, "I have a German passport, and if things are still running this way, I have a chance to play for Rudi Völler."

[55] Klose's international debut came on 24 March 2001 in a 2002 FIFA World Cup qualifier against Albania;[56] in the 73rd minute, Germany head coach Rudi Völler put him in as a substitute.

Two hat-tricks against Israel and Austria in friendlies prior to the upcoming World Cup were enough to establish him in Germany's starting line-up for the tournament.

[58] Klose came to international prominence at the 2002 World Cup in Korea–Japan with five headed goals for Germany, finishing as the joint second-highest goalscorer alongside Rivaldo.

Klose also became the first player to score five headers in a FIFA World Cup, and he celebrated two of his goals with his trademark front-flip, earning him the nickname "Salto-Klose" (German: Salto = somersault).

[60] Klose participated in UEFA Euro 2004 and came on as a substitute in two matches, against Latvia and the Czech Republic, but was not completely fit, since he had just recovered from a knee injury.

[63] Klose scored an 80th-minute headed equaliser against Argentina in the quarter-finals, and Germany won the resulting penalty shootout.

[64] With five goals, he finished as the top scorer of the tournament, taking home the FIFA World Cup Golden Boot.

[65] At Euro 2008, Klose started the opening group stage match against Poland and assisted Lukas Podolski's two goals in a 2–0 victory.

[69] Klose made his 100th international appearance in the quarter-final match against Argentina, becoming only the sixth German player to reach the landmark.

He then scored the second and fourth goals against Argentina (Germany winning 4–0), pulling him level with Gerd Müller's all-time German World Cup goalscoring record.

[70] During the Euro 2012 qualifiers, Klose scored at least one goal in every single game he played, striking against all of Germany's opponents: Belgium, Azerbaijan, Turkey, Kazakhstan and Austria.

[73] Klose again had to come off the bench in the semi-final against Italy, but failed to add to his goal tally as Germany were eliminated with a 2–1 loss.

[82] Klose started in the World Cup final against Argentina and played until the 88th minute, when he was substituted for Mario Götze.

In the past few months, I have thought a lot about continuing my playing career, but also about pursuing other avenues, namely becoming a coach.

[88] On 17 June 2022, it was announced that Klose would take over as head coach of Austrian Bundesliga club Rheindorf Altach.

[95] In his prime, he was also a quick player who was known for his turn of pace, movement, and positional sense in the penalty area, which enabled him to lose his markers and get on the end of crosses.

[105] On 30 April 2005, while playing for Werder Bremen, Klose refused to accept a penalty given against Arminia Bielefeld as he felt the decision was incorrect.

He admitted this to the referee, who took back his decision to award the goal, spared Klose from a yellow card and shook his hand.

[106][107] Later that year, he was once again given a fair play award for his actions by the German Football Association, later commenting, "The referee asked me if I had touched the ball with my hand and it was not a problem for me to answer 'yes'.

"[108] In 2016, he was given the Sport Ethics Award for his honesty at the University of Rome Tor Vergata, and subsequently added regarding the incident, "Napoli?

[110][111] In a 2007 interview with Der Spiegel, he stated that at home, he and his wife speak Polish to their children, who learn German in school.