Guerrero was born in Lima. He started playing football in the lower categories of Peruvian club Alianza Lima. In 2003, Guerrero signed a contract with Bavarian giants Bayern Munich. During 2003–04, Guerrero played in the Regionalliga Süd. He played 23 games and scored 21 goals. During the 2004–05 season, he joined fellow countryman, Claudio Pizarro, on the Bayern first team. In June 2006, it was announced that Guerrero had transferred to Hamburger SV, and signed a contract with the club through 2010. He scored the winner against his former club Bayern Munich, which he did not celebrate because of his past with the club and the endearment he still felt for it. The result meant that Bayern had no chance of playing in the Champions League in the 2007–08 season.
Guerrero joined Hamburg in 2006 from Bayern Munich. His first season was marred by an injury, which took away half his season, and his low productivity, being a sub most of the season. Near the end he did score three goals, making his season total five goals in 20 games. One of these goals was against former club Bayern Munich in a 1–2 victory which left Bayern with no possibilities of making it to the Champions League. In the 2007–08 season, his second at Hamburg, Guerrero played 29 of 34 games in the Bundesliga, scoring nine goals and getting four assists, as well as becoming an undisputed starter and a vital part of Hamburg. He was the third top scorer, behind Rafael van der Vaart (12 goals) and Ivica Olić (14 goals). In the UEFA Cup and Qualification he played nine games, scoring five goals and getting three assists. His first hat-trick in his professional career was against Karlsruher SC, in the last game of the Bundesliga, scoring the second, third, and fourth goals in a 7–0 victory. This victory secured them fourth place and a UEFA Cup spot for next season. By the beginning of the 2008–09 season, Guerrero had become first choice striker for Hamburger SV. Coach Martin Jol even went as far as saying that Guerrero better not catch even a cold during the season. Guerrero was fined a club record (somewhere in the region of €50,000–100,000) in April 2010 for an incident at the end of a league game with Hannover 96, where after apparently having been abused by a Hamburg fan, Guerrero threw his drinks bottle into the crowd, striking said fan in the face. The German Football Association suspended Guerrero for five league games and fined him a further €20,000.
Guerrero joined Corinthians (football club) in 2012 from Hamburger SV. He scored both of Corinthians' goals in the 2012 FIFA Club World Cup, once in the semi-finals against Al Ahly SC and the winning goal in the final against Chelsea. In May 2013, Guerrero became the first Peruvian footballer to ever be on the cover of Placar magazine, Brazil's biggest football magazine. The cover featured Guerrero as a warrior ("guerrero" is similar to the Portuguese word "guerreiro", which means "warrior") fresh out of battle, with blood on his legs, and carrying a Corinthians flag.
Paolo Guerrero's career with the Peruvian national team began in the doomed Germany 2006 campaign, but he managed to score twice for the national side. His first goal became the winner against Chile in Lima's Estadio Nacional. It was followed by a first minute goal in the next match against Ecuador in the same venue, though the Ecuadorians fought back to secure a 2–2 away draw. However, Guerrero was ruled out of Peru's first two 2010 FIFA World Cup qualifying games because of injury. A further blow to Peru was laid down by FIFA when Guerrero was suspended 6 games for insulting the referee during the Uruguay vs. Peru game in June 2008. The suspension started with the Peru vs. Venezuela game in September.
Following Peru's disastrous qualifying campaign for the 2010 World Cup, José del Solar was replaced by Uruguayan manager Sergio Markarian and Guerrero was called up for the 2011 Copa America. In line of an injured Pizarro, Guerrero played as the team's starting striker in the Competition and scored five times, one each against Uruguay and Mexico followed by a hat trick against Venezuela in the Third Place play-off match which Peru won 4–1. He became the tournament's top goalscorer.