In 2006, King won her only WTA Tour singles title at the Bangkok Open, a Tier-III tournament where she defeated Tamarine Tanasugarn in the final.

In 2009, she reached the mixed-doubles final at the French Open alongside Brazilian player Marcelo Melo, losing to top-seeded team Liezel Huber/Bob Bryan.

She played in the ladies' doubles with Anna-Lena Grönefeld, losing in the quarterfinals to eventual champions Venus and Serena Williams.

In the doubles tournament, she and partner Michaëlla Krajicek were seeded third and won the title without dropping a set, defeating Bethanie Mattek-Sands and Shaughnessy in the final.

King partnered with Julie Coin and reached the quarterfinals of the doubles tournament, before losing to third seeds Petrova and Samantha Stosur, who went on to become the runners-up.

Her next Premier event was the Charleston Open, where she reunited with Krajicek and reached the final, before falling to top seeds Huber and Petrova.

They defeated fourth seeds Huber and Anabel Medina Garrigues, before falling in the quarterfinals to Pe'er and Francesca Schiavone.

In the doubles tournament, she partnered with Alizé Cornet and won the title after an injury to Lucie Hradecká forced top seeds Hradecká/Chuang to retire in the second round.

In singles, King defeated second seed Elena Vesnina in the first round and reached the semifinals, falling there to Kristina Barrois.

She entered the mixed-doubles tournament with Christopher Kas, reaching the semifinals, before falling to Shvedova and Julian Knowle.

At Wimbledon, King won the ladies' doubles title in straight sets with Yaroslava Shvedova.

At the US Open, King and Shvedova won their second Grand Slam doubles title, defeating the second-seeded pair Huber/Petrova in a rain-delayed final.

[3] King and Shvedova made the finals of the US Open, losing to Liezel Huber and Lisa Raymond.

King made it to the finals of five other WTA tournaments in the course of the year, one in Monterrey with Grönefeld and in Rome, Cincinnati, Osaka, and Moscow with Shvedova.

She partnered with Barbora Strýcová in Florianópolis, and they made it to the semifinals before being defeated by Medina Garrigues and Shvedova.

Partnering Zheng Jie, she made a quarterfinal appearance in Madrid, losing to Sara Errani and Roberta Vinci.

The highlight of her year came on hardcourts in Waco, where King and Nicole Gibbs won in November, defeating Julia Glushko and Rebecca Peterson.

At the Australian Open, King and Shvedova advanced to the third round, where they lost to Mirjana Lučić-Baroni and Andrea Petkovic.