Pellegrini's journey in swimming started early when her parents introduced her to a pool. By 2003, she was competing internationally for Italy. Her dedication and talent quickly became evident as she made a name for herself in the swimming world.

| Season | Event | Rank |
|---|---|---|
| 2021 | Mixed 4 x 100m Medley Relay | 4 |
| 2021 | Women's 4 x 100m Medley Relay | 6 |
| 2021 | Women's 200m Freestyle | 7 |
| 2016 | Women's 200m Freestyle | 4 |
| 2016 | Women's 4 x 100m Freestyle Relay | 6 |
| 2016 | Women's 4 x 100m Medley Relay | 8 |
| 2016 | Women's 4 x 200m Freestyle Relay | 13 |
| 2012 | Women's 200m Freestyle | 5 |
| 2012 | Women 400m Freestyle | 5 |
| 2012 | Women's 4 x 200m Freestyle Relay | 7 |
| 2012 | Women's 4 x 100m Medley Relay | 11 |
| 2012 | Women's 4 x 100m Freestyle Relay | 12 |
| 2008 | Women's 200m Freestyle | G Gold |
| 2008 | Women's 4 x 200m Freestyle Relay | 4 |
| 2008 | Women 400m Freestyle | 5 |
| 2008 | Women's 4 x 100m Freestyle Relay | 10 |
| 2008 | Women's 4 x 100m Medley Relay | 14 |
| 2004 | Women's 200m Freestyle | S Silver |
| 2004 | Women's 100m Freestyle | 10 |
| 2004 | Women's 4 x 100m Freestyle Relay | 10 |
| 2004 | Women's 4 x 100m Medley Relay | 16 |
| 2004 | Women's 50m Freestyle | 74 |
Among her most notable accomplishments are winning gold in the 200m freestyle at the 2008 Olympic Games in Beijing and the 2019 World Championships in Gwangju, South Korea. These victories stand out as highlights in her illustrious career.
Pellegrini credits her family and coach Alberto Castagnetti as the most influential figures in her career. She also looks up to Swiss tennis player Roger Federer and Italian motorcyclist Valentino Rossi as her idols.
In late 2014 and early 2015, Pellegrini faced a back injury that required surgery later in 2015. Despite this setback, she continued to perform at a high level, showcasing her resilience and determination.
Pellegrini has received numerous accolades throughout her career. She was named Female Athlete of the Year at the 2019 Gazzetta Sports Awards in Italy. In 2018, she received the Giulio Onesti Award and the Cangrande d'Oro Award. She was also named Woman of the Year in 2017 by fellow Italian athletes.
Additionally, Pellegrini served as Italy's flag bearer at the opening ceremony of the 2016 Olympic Games in Rio de Janeiro. She was named European Female Athlete of the Year by the International Sports Press Association (AIPS) in 2011 and World Female Swimmer of the Year by Swimming World Magazine in 2009.
Pellegrini achieved several milestones during her career. She became the first swimmer to win eight world championship medals in the same individual event from 2005 to 2019. She was also the first Italian swimmer to win six or more career world championship medals.
At the 2008 Beijing Olympics, she became the first female Italian swimmer to win an Olympic gold medal. In 2004, at just 16 years old, she won silver in the 200m freestyle at the Athens Olympics, making her the youngest Italian swimmer to win an Olympic medal.
Pellegrini retired from competitive swimming in November 2021 after winning the 200m freestyle at the Italian winter short course championships. Reflecting on her retirement, she expressed happiness with how her farewell went despite missing public spectators.
The disappointment of missing out on a medal at the 2016 Rio Olympics motivated Pellegrini to push harder. She went on to win gold at the world championships in 2017 and again in 2019, feeling more comfortable with her speed and training.
Beyond swimming, Pellegrini has been active in various roles. She was elected to the International Olympic Committee (IOC) Athletes' Commission during the Tokyo 2020 Olympics. She also appeared as a judge on 'Italia's Got Talent' and owns a restaurant called Tacco 11 in Venice, which she opened with her family in 2011.
Federica Pellegrini's journey from a young swimmer to an accomplished athlete is inspiring. Her achievements, resilience through injuries, and contributions beyond swimming highlight her remarkable career.Pellegrini's journey in swimming started early when her parents introduced her to a pool. By 2003, she was competing internationally for Italy. Her dedication and talent quickly became evident as she made a name for herself in the swimming world.