In February 2010, she reached the doubles final of the $50k+H Biberach tournament, partnering Carmen Klaschka, losing to Stéphanie Cohen-Aloro and Selima Sfar.

In order to play in the main draw, Barthel had to qualify, which she did by defeating Mariya Koryttseva, Julie Coin, and Varvara Lepchenko.

[12] At the Qatar Total Open in Doha, Barthel was defeated in the second round by top seed and eventual champion Victoria Azarenka.

At the first Premier Mandatory event of the year at the BNP Paribas Open in Indian Wells, Barthel earned a comfortable first-round victory over American Jill Craybas.

[15] At the Sony Ericsson Open, Barthel reached the third round by beating Gréta Arn and thirteenth seed Jelena Janković.

[18] Barthel recorded her first victory against a top 10 player by defeating world number seven and seventh seed Marion Bartoli in the second round.

[21] Seeded thirtieth at the French Open, Barthel suffered a first-round upset at the hands of American qualifier Lauren Davis.

[31] Seeded third at the Challenge Bell in Quebec City, Barthel advanced to the semifinals where she lost to eventual champion Kirsten Flipkens.

Seeded eighth, she reached the semifinals after wins over qualifier Grace Min, Eleni Daniilidou, and Johanna Larsson.

[35] As the ninth seed and defending champion at the Moorilla Hobart International, Barthel again reached the final by defeating Australian wildcard Ashleigh Barty, Chanelle Scheepers, Tsvetana Pironkova, and Kirsten Flipkens.

[41] At the Premier Mandatory event in Indian Wells, Barthel made it to the fourth round, including wins over Kiki Bertens and former world number one and eleventh seed Ana Ivanovic.

[44] Representing Germany for the first time, Barthel traveled to Stuttgart to play the Fed Cup World Group play-offs versus Serbia.

After Sabine Lisicki and Anna-Lena Grönefeld beat the Serbian doubles team, it secured Germany their place in the 2014 Fed Cup World Group.

[46] In doubles, she partnered with fellow German Sabine Lisicki where they beat experienced players, Bethanie Mattek-Sands and Sania Mirza in the final.

[51] As the top seed at the Gastein Ladies, Barthel retired from her second-round match versus Austrian wildcard Lisa-Maria Moser due to a shoulder injury.

[68] Barthel went to Paris to defend her title at the Open GDF Suez, but she lost in the first round to eighth seed Kirsten Flipkens.

Barthel added further disappointment to her season with a first round defeat at the Qatar Total Open to compatriot Annika Beck.

At the Italian Open, Barthel was defeated in the first round by tenth seed and eventual finalist Carla Suárez Navarro.

[118] Barthel only played one grass-court tournament before Wimbledon, at Eastbourne where she lost in the first round to eventual champion Belinda Bencic.

She reached the final for the second year in a row beating Kiki Bertens, Maryna Zanevska, Rebecca Peterson, and Lara Arruabarrena.

[132] Barthel, as the fifth seed, reached the quarterfinals at the Korea Open defeating wildcard Jang Su-jeong[133] and Mariana Duque Mariño.

[136] However, in doubles, Barthel and fellow German Laura Siegemund defeated Spaniards Anabel Medina Garrigues and Arantxa Parra Santonja in the final.

[151] As the top seed at the Advantage Cars Prague Open, Barthel retired in her quarterfinal match after losing the first set to qualifier and compatriot Antonia Lottner.

Playing in Austria at the Generali Ladies Linz, Barthel was defeated in the first round by fourth seed Carla Suárez Navarro.

[177] Barthel qualified for the main draw at the Eastbourne International beating Beatriz Haddad Maia and Kristína Kučová.

Here, she reached the semifinal after wins over Kateryna Kozlova, third seed and defending champion Tímea Babos, and qualifier Ysaline Bonaventure.

[191] In Indian Wells at the BNP Paribas Open, Barthel was defeated in the second round by fourth seed Elina Svitolina.

[195] Barthel retired in the final round of qualifying at the Mutua Madrid Open to Sílvia Soler Espinosa due to injury.

[217] Competing in Germany at the Nürnberger Versicherungscup, Barthel was defeated in the second round by top seed and eventual champion Yulia Putintseva.

Ranked 96 at the Wimbledon Championships, Barthel suffered a first-round defeat at the hands of lucky loser Marie Bouzková.