Her best results include a title in the 2005 German Junior Open (Grade 1), a tournament in which she was finalist the year before, defeating Erika Zanchetta in three sets in the final, and a runner-up place in the 2006 Trofeo Bonfiglio (Grade A), where she lost in the final to compatriot Ioana Raluca Olaru after having defeated the top-ranked world junior player Anastasia Pavlyuchenkova in the semifinals.

She beat Martina Müller in the second round, Eleni Daniilidou in the quarterfinals and Karin Knapp in the semifinals before losing to Gisela Dulko in the final.

The following month, Cîrstea played in the junior tournament of the 2007 French Open where she reached the doubles final with Alexa Glatch, losing to the third seeds Ksenia Milevskaya and Urszula Radwańska.

At the Estoril Open, Cîrstea reached the quarterfinals of the singles tournament, defeating Kimiko Date-Krumm and Maret Ani, before falling to the eventual champion Yanina Wickmayer.

She began with wins over Carly Gullickson and an upset of the 21st seed Alizé Cornet to advance to the third round of a Grand Slam tournament for the first time.

Cîrstea continued her unlikely run with a 3–6, 6–0, 9–7 upset over the fifth-seeded Jelena Janković to reach her first Grand Slam quarterfinal,[9] where she faced the 30th seed Sam Stosur, losing in straight sets.

At the Cincinnati Masters, she defeated Meghann Shaughnessy and Anna-Lena Grönefeld before losing to the fourth seed Elena Dementieva, but achieved a career high ranking of No.

At the ITF Bucharest, Cîrstea beat her compatriots Diana Enache and Mădălina Gojnea, before losing in the third round to Laura Pous Tió.

In Dallas, the inaugural tournament of Texas Tennis Open, Cîrstea beat Jarmila Gajdošová in the first round, in the second she lost to Aravane Rezaï.

She defeated Estrella Cabeza Candela, Eva Fernández Brugués, Laura Pous Tió and Stefanie Vögele, before beating Silvia Soler Espinosa in straight sets.

In France, Cîrstea won a $50k tournament featuring top 100 players where she defeated Paula Ormaechea, Stefanie Vögele, Michaëlla Krajicek, Akgul Amanmuradova, and Sofia Arvidsson.

At the Internazionali BNL d'Italia, Cîrstea defeated Jelena Janković in the first round and Sofia Arvidsson in the second before losing in three sets to Petra Kvitová.

[6] At the Bank of the West Classic in San Jose, Sorana as the ninth seed beat Vania King and lucky loser Zheng Saisai.

In the Rogers Cup en route to reaching her first final in five years, Cîrstea beat two former number-one players, Caroline Wozniacki and Jelena Janković, and former Grand Slam champions Petra Kvitová and Li Na.

Cîrstea was the top seed at Baku Cup and defeated Tunisian wildcard Ons Jabeur in the first round but then lost to eventual semifinalist Stefanie Vögele 1–6, 1–6.

In Guaruja, she beat Oleksandra Korashvili, Rebecca Šramková, Jil Teichmann, and third seed Beatriz Haddad Maia before losing to Montserrat Gonzalez in three sets in the final.

She defeated Yvonne Cavallé Reimers, Martina Caregaro, and Jil Teichmann en route to the semifinals where she lost to Sara Sorribes Tormo.

[54] Receiving a wildcard for the Madrid Open, Cîrstea reached the quarterfinals beating Jelena Jankovic, Danka Kovinić and Laura Siegemund en route.

Her first tournament of the grass court season was at Eastbourne, where she entered the main draw as a lucky loser following the withdrawal of CoCo Vandeweghe; she lost to Hsieh Su-wei in the final qualifying round.

At Beijing, she reached the quarterfinals, defeating Mona Barthel, Christina McHale, and Karolína Plíšková; the latter win was her first against a top ten opponent since 2014.

At her home tournament in Bucharest, she reached the quarterfinals by defeating Çağla Büyükakçay and Maryna Zanevska, before falling to first seed and eventual champion Anastasija Sevastova.

At the Rogers Cup in Montreal, in a mirror of her results in Indian Wells, she defeated Monica Niculescu in the first round, before losing to Venus Williams.

Her final event of the year was at the ITF tournament in Dubai, where she defeated Yuliya Hatouka, before falling to the eventual champion Peng Shuai.

She had a strong run to the semifinals of Nuremberg, defeating Kirsten Flipkens, Laura Ioana Paar, and Nina Stojanović, before falling to the eventual champion Yulia Putintseva.

She defeated Denisa Allertová, Ysaline Bonaventure, Danka Kovinić, and Katarina Zavatska, before losing in the final to Alison Van Uytvanck in three sets.

Her final tournament of the year was the 125K at Limoges, defeating Tatjana Maria and Sara Sorribes Tormo to reach the quarterfinals, where she lost to Nicole Gibbs.

[91] At the Australian Open, she scored her first top 10 victory since 2017 by defeating ninth seed, three-time Grand slam winner, and 2019 finalist, Petra Kvitová, in the second round.

[133] At the 2023 Dubai Tennis Championships she defeated 11th seed Beatriz Haddad Maia in the longest match of the season thus far lasting 3 hours and 29 minutes.

83 at the next WTA 1000 2023 BNP Paribas Open, for a second consecutive year she reached the fourth round defeating Kimberly Birrell, 19th seed Madison Keys by walkover, and Bernarda Pera.

According to the Tennis Spy, her long stride means she covers ground while not appearing to move particularly quickly, allowing her to execute her game style excellently.