Her other highlights in doubles include winning the 2010 WTA Finals with Dulko and finishing runner-up at the 2005 and 2014 US Open tournaments, partnering respectively with Elena Dementieva and Martina Hingis.

After winning the 2015 US Open, Pennetta announced she would retire at the end of the season, playing her last tournament at her WTA Finals singles debut.

The following week at the clay-court tournament in Sopot, Poland, Pennetta won her first WTA Tour title, defeating Klára Koukalová in the final.

Pennetta started to pick up her pace as the season went on, with two runner-up showings at Bogotá and Acapulco, losing to Lourdes Domínguez Lino and Anna-Lena Grönefeld, respectively.

Pennetta begun 2007 with three first-round loses at Gold Coast, Hobart and the Australian Open, falling to Maria Kirilenko, Aiko Nakamura and Kaia Kanepi, respectively.

Her next two tournaments went well, as she has a semifinal showing at Bogotá (falling to Roberta Vinci) and made it all the way to the final of Acapulco, where she lost to Émilie Loit.

[4] Pennetta won her first title of the year at the Cachantún Cup in Viña del Mar, Chile, defeating Klára Zakopalová in the final.

[4] Pennetta then reached the quarterfinals of Commonwealth Bank Tennis Classic in Bali, losing to eventual runner-up Tamira Paszek.

[4] At her first tournament of the year on clay, the Copa Sony Ericsson Colsanitas in Bogotá, Pennetta fell to Maša Zec Peškirič in the first round.

She was the 15th seed at the BNP Paribas Open in Indian Wells, the first Premier Mandatory event of the year, and lost in the fourth round to eventual runner-up Ana Ivanovic in a three-set match.

She then played two matches for Italy's Fed Cup team in the World Group semifinals versus reigning champion Russia.

The following week, she reached the semifinals of the Porsche Tennis Grand Prix in Stuttgart beating two top-ten players, Jelena Janković and Nadia Petrova, but fell to world No.

On the hard courts of Los Angeles, Pennetta upset Vera Zvonareva en route to the semifinals where she would be extended to three sets by Maria Sharapova.

[5] At Cincinnati, a Premier-5 event, she extended her winning streak to 15 matches, maintaining an impressive record against Venus Williams, whom she beat in two sets.

In the Medibank International, she notched up two top-20 wins over Sam Stosur and Li Na, before losing to unseeded Aravane Rezaï in the quarterfinals.

After receiving a first-round bye she defeated Alisa Kleybanova and Tathiana Garbin to reach the semifinals, where she fell in three sets to Lucie Šafářová.

In her second-round match, she defeated Lourdes Domínguez Lino before Pennetta came up victorious against Shahar Pe'er in a three-set battle, in which she rallied from deficits several times.

In the Fed Cup, she helped two-time reigning champion Italy defeat Australia with wins in two singles rubbers over Sam Stosur and Jarmila Groth.

[9] As the 21st seed at the Wimbledon Championships, Pennetta eased past Chanelle Scheepers in two sets before seeing off Evgeniya Rodina to reach to the third round.

Unseeded at the Rome Masters, Pennetta reached the quarterfinals after defeating Maria Kirilenko, Sloane Stephens, and Petra Cetkovská.

The week before the French Open, Pennetta qualified for the Internationaux de Strasbourg and reached the semifinals where she lost to Lucie Hradecká.

Pennetta was ranked 83rd entering the US Open and she reached her first Grand Slam singles semifinal, defeating higher-ranked opponents such as Errani, Kuznetsova, Halep and Vinci in early rounds before succumbing to world No.

In Dubai she reached main draw and then defeated Kaia Kanepi and 2nd seed Agnieszka Radwańska, before losing the match against Venus Williams in quarterfinals.

Playing in front of her home crowd at the Internazionali BNL d'Italia, she reached the third round after defeating Yvonne Meusburger and Belinda Bencic.

In doubles, she partnered with Hingis and they reached the final, losing to Russian duo Ekaterina Makarova and Elena Vesnina in three sets.

In October, Pennetta was seeded 15th at the Wuhan Open; she lost in the first round to Jarmila Gajdošová in straight sets, but won the doubles tournament with Hingis.

Accumulating a record of 2–1, she advanced to the semifinal for the first time since Indian Wells in March where she avenged her loss to Suarez Navarro, claiming the victory in straight sets.

As the defending champion at Indian Wells, she managed to reach the quarterfinals, beating Madison Brengle, Sam Stosur, and world No.

At Cincinnati, Pennetta beat former top-ten player Dominika Cibulková before losing to newly crowned Toronto champion Belinda Bencic in straight sets.

She made it to the quarterfinals for the sixth time in the previous seven attempts by beating Jarmila Gajdošová, Monica Niculescu, Petra Cetkovská and 2011 champion, Samantha Stosur.