Pep Strategy

After leading the 'B' side to promotion to Segunda División B, Guardiola revealed that Ronaldinho, Deco, Samuel Eto'o and others were not part of his plans for next season. By the time of the announcement, Guardiola had already offloaded full back Gianluca Zambrotta to Milan, attacking midfielder Giovani dos Santos to Tottenham Hotspur, and midfielder Edmílson to Villarreal. Deco went to Chelsea, while the iconic Ronaldinho was sold to Milan. Lilian Thuram was going to Paris Saint-Germain but the discovery of a heart condition put a stop to the move, and the veteran retired to tend to his health. Oleguer Presas signed with Ajax, Santiago Ezquerro was released by Barça and Marc Crosas was sold to Celtic. The fate of Samuel Eto'o took much of the summer to unravel, with the Cameroonian linked with several clubs, but Guardiola finally declared that he would stay after his dedication in training and participation in the pre-season.

Under Guardiola's new leadership, several new signings were made. Dani Alves and Seydou Keita arrived from Sevilla, Martín Cáceres from Villarreal by way of Recreativo, Gerard Piqué returned from Manchester United, and Aliaksandr Hleb was signed from Arsenal. Henrique was also signed from Palmeiras, but was immediately loaned out to Bayer Leverkusen.

Guardiola's first competitive game as coach was in the third qualifying round of the Champions League, in which Barça comfortably beat Polish club Wisła Kraków 4–0 at home. FC Barcelona was defeated 1–0 in Kraków, but progressed with a 4-1 aggregate victory. Promoted Numancia also defeated FC Barcelona in the opening match-day of the La Liga, but the team then went on an undefeated streak for over 20 matches to move to the top of the league. Barça would maintain their spot atop La Liga's table, securing their first league title since 2006 when Real Madrid lost at Villareal on May 16, 2009.
Josep Guardiola celebrating Barcelona's 2009 UEFA Champions League Final with Manuel Estiarte.

The league title was the second piece of silverware in Guardiola's first season at the Camp Nou. On May 13, 2009, Barcelona won the Copa del Rey, defeating Athletic Bilbao 4-1.

Guardiola finished the season by leading Barça to the final of the Champions League, where they beat Manchester United 2–0. In doing so, they became the first Spanish club to win the domestic cup, league, and European club titles (the treble) in the same season. Furthermore, Guardiola became the youngest coach ever to coach a Champions League winning team.

Guardiola has shown preference to playing a 4-3-3 system, the same system used by Frank Rijkaard. In interviews with the press, his players stressed a harder work ethic than before, but also a more personal approach during training and a closer relationship with their new coach.

On September 26, FC Barcelona gave Pep Guardiola his 50th professional victory, away against Málaga.

Later, Guardiola would coach the first team to 6 title victories in one year, becoming the first manager ever to do so. These include the Spanish League, Copa del Rey, Champions League, Spanish Super Cup, European Super Cup, and World Club Cup.

On 20 January 2010, Guardiola agreed to a one-year contract extension that would keep him with Barcelona until the end of the 2010-11 season.