Singles

Begu made her ITF Women's Circuit debut at a $10k event at Bucharest in May 2005. In September 2006, she reached her first ITF final at Bucharest, but lost to Alexandra Cadanțu. Year later, she won her first ITF title at Brașov, defeating Andreea Mitu in the final. In October 2008, she won her first major ITF title at the $50k event in Jounieh, defeating Anastasiya Yakimova in the final. During the season of 2008, she was climbing more and more on the rankings, getting from top 800 to top 250 at the end of the year. At the 2009 French Open, she had her first major attempt to participate in the main draw, but failed in the final stage of the qualifications. In July 2009, she made her WTA Tour debut at the Hungarian Open, but lost to Shahar Pe'er in the first round.

Doubles

She made her ITF Circuit doubles debut at a $10k event in Câmpina in September 2005. In July 2006, she won her first ITF title at Galați. In May 2009, she won her first major ITF title at the $100k Bucharest, alongside Simona Halep. At the 2009 Palermo Ladies Open, she made her WTA Tour doubles debut. In August 2010, she won the $75k Bucharest, alongside Elena Bogdan. Later that year, she won three $25k titles and finished runner-up at the $50k event in Madrid and the $75k Toyota World Challenge.

Singles

Begu continued to progress at the ITF Circuit, winning her first $100k title at the Copa Bionaire in Cali in February, after defeating Laura Pous Tió, in straight sets in the final. In April, as a qualifier, she reached her first WTA final at the Andalucia Tennis Experience. On her way to the final, she defeated top 40 Klára Koukalová and top 20 Svetlana Kuznetsova, before losing to Victoria Azarenka in the final.^[3] At the French Open, she made her Grand Slam main-draw debut and recorded her first Grand Slam win. She lost to Svetlana Kuznetsova in the second round. In June, she returned to the ITF Circuit, where she reached the final of the $100k Open de Marseille, being defeated by Pauline Parmentier. Then, she returned to the WTA Tour and reached another WTA final at the Hungarian Open, but lost to Roberta Vinci.^[4] After that, she won the $100k Bucharest event, defeating Laura Pous Tió in the final. She reached the semifinals of the Texas Open, where she lost to Sabine Lisicki. During the year, she progressed at the rankings, debuting in the top 100 in April and later in the top 50 in July.

Begu continued to progress on the WTA Tour. In March, she reached the semifinal of the Mexican Open in Acapulco, but lost to Flavia Pennetta. In April, she reached the quarterfinals of the Morocco Open, where she also defeated former world No. 2, Svetlana Kuznetsova. In July, she reached another WTA semifinal at the Palermo Ladies Open, losing to Sara Errani in straight sets. Despite falling early at the US Open, she made her first top-10 win, defeating world No. 9, Caroline Wozniacki, in the first round. In the following round, she lost to Sílvia Soler Espinosa. She did even better in September, when she won her first WTA Tour title, defeating Donna Vekić in the final. There, she also defeated top-50 players Alizé Cornet and Urszula Radwańska. She followed this with semifinal of the Linz Open, where Victoria Azarenka defeated her.

Doubles

Begu started year of 2011 well, winning title at the $100k Cali, as her first doubles tournament of the year. In June 2011, she won another $100k title in Marseille. At the 2011 Wimbledon Championships, she made her Grand Slam doubles debut, but lost in the first round. In July 2011, she won her year-third $100k title in Bucharest. She started year of 2012 with the title at the Hobart International, that was her first WTA doubles title. There she partnered with Monica Niculescu. She followed this with quarterfinal of the Australian Open, again with Niculescu. Then, in April, she reached final of the Morocco Open, but finished runner-up with Alexandra Cadanțu. In July, she won $100k Bucharest for the second year in-a-row. She finished year with final at the Luxembourg Open. During these two seasons, Begu was climbing at the rankings. First, she debuted in the top 100 in February 2011, then in the top 50 in late January 2012.

Singles

Unlike previous years, Begu did not made any progress during the season of 2013. She started year with first round loss at the Hobart International. After that, she reached only first or second round at every tournaments with the exception of the one quarterfinal at the Korea Open in September. There she defeated top 50 Julia Görges, but later lost to Anastasia Pavlyuchenkova.^[5] Weak results caused her dropping on the rankings and falling out the top 100 in the September.^[6]

Things got changed in the season of 2014. At the Australian Open, she was forced to play in the qualifications. She succeed to qualify, but then lost to Galina Voskoboeva. At her following participation, she reached quarterfinal of the Rio Open, losing there to Teliana Pereira.^[5] She then was successful at the ITF Women's Circuit. She won two $25k events and reached final of the $50k Medellín.^[7] Nearly after that, in May, she reached semifinal of the Portugal Open in Oeiras, defeating top 30 Kaia Kanepi and top 50 Kurumi Nara, before she lost to top 20 player Carla Suárez Navarro.^[5] In July, she won $100k Contrexéville Open, after defeating seed No. 1 Kaia Kanepi.^[7] She finished year with the final of Premier-level Kremlin Cup, but then lost to Anastasia Pavlyuchenkova.^[8] All these results, helped her to climbed from outside the top 120 to the top 50, at the end of the year.^[6]

Doubles: Three WTA Tour titles

Just like in singles, Begu did not show her best in doubles, during these two seasons. At the 2013 Australian Open, she reached third round, alongside Niculescu, failing to repeat previous year quarterfinal result. In June, she won title at the Rosmalen Championships, alongside Anabel Medina Garrigues. That was her first grass title. In February 2014, she won title at the Rio Open, alongside María Irigoyen.^[5] Soon after that, she returned at the ITF Women's Circuit, where she first win $25k event in São Paulo and then the $50k Medellín Open.^[7] When she returned to the WTA Tour, she did not do well, but later reached third round of the French Open.^[5] In July, she reached final of the $100k Contrexéville Open.^[7] In September, she reached semifinals at the Tashkent Open, followed with title at the Korea Open.^[5] Despite her inconsistent, she remained in the top 100 through whole 2013 and 2014 seasons.^[6]

Singles

Begu made big progress at the 2015 Australian Open. Until then, she had second round as her best Grand Slam result, but then she reached her first third round, and later round of 16.^[5] In the first round, she defeated top 10 Angelique Kerber, but later failed to reach her first Grand Slam quarterfinal, losing to world No. 7, Eugenie Bouchard.^[9] A month later, she reached the semifinal of the Rio Open, but lost to Anna Karolína Schmiedlová.^[5] She started well clay-season with quarterfinal of the Premier-level Charleston Open, where she was defeated by Angelique Kerber.^[10] At the Madrid Open, she reached her first Premier Mandatory quarterfinal, losing there to world No. 4, Petra Kvitová. She then reached third rounds at the Italian Open, French Open and Wimbledon. In September, she won WTA title at the Korea Open, defeating qualifier Aliaksandra Sasnovich in the final.^[5] In May, she debuted in the top 30 and later reached place of 25 as her then-highest ranking.^[6]

Despite having a slow start at the season of 2016, Begu reached round of 16 at the Miami Open. There she defeated top 40 Sabine Lisicki, before she later lost to Madison Keys.^[5] She followed this with quarterfinal of the Premier-level Charleston Open, losing to Angelique Kerber.^[11] She then made her second consecutive Madrid Open quarterfinal. She defeated world No. 4 Garbiñe Muguruza in the second round,^[12] but later lost to her compatriot, Simona Halep.^[13] She then reached her first Premier 5 semifinal at the Italian Open. There she made another top 10 win over Victoria Azarenka,^[14] but later lost to Serena Williams.^[15] At the French Open, she reached round of 16, after defeating two top 50 players, CoCo Vandeweghe and Annika Beck,^[16] but later lost to Shelby Rogers.^[17] In August, she won title at the Brasil Tennis Cup, after defeating Tímea Babos in the final.^[18] There she also defeated top 50 Monica Puig.^[19] Soon after that, also in August, she reached her career-highest singles ranking of place 22.^[6]

Until April 2017, Begu did not made any significant results since the start of the season. She then reached quarterfinal of the Premier-level Charleston Open, including win over top 20 Samantha Stosur, right before she later lost to Daria Kasatkina. She followed this with semifinal of the Istanbul Cup, but then lost to Elise Mertens. At the Madrid Open, she reached third round and also defeated top 20 Elena Vesnina in the first round. In July, she reached final of the $100k Southsea Trophy, but then lost to Tatjana Maria. Nearly after that, she won title at the Bucharest Open, defeating top 50 Julia Görges in the final and not losing a single set in the entire tournament.^[20] In the semifinal, she defeated top 40 Carla Suárez Navarro. She then did not do well, but in October, she reached semifinal of the Premier-level Kremlin Cup, where she was defeated by Daria Kasatkina. Previously, in the second round, she defeated top 30 Anastasija Sevastova. Through whole of the year, she stayed in the top 70.^[6]

Doubles

In February 2015, Begu finished as runner-up at the Rio Open, alongside Maria Irigoyen. At the Madrid Open, she reached her first Premier Mandatory quarterfinal. At the 2015 Canadian Open, she reached first Premier 5 quarterfinal, and then at the 2015 Wuhan Open, alongside Monica Niculescu, she reached her first final from that level. They lost to Martina Hingis and Sania Mirza. She finished season with the final of the Premier-level Kremlin Cup. Right after that, she debuted in the top 30. The following year, she continued with significant performances at the Premier 5-level, reaching semifinal at the 2016 Italian Open. However, her other results during the season of 2016 was not such significant. She started year inside top 30, then start dropping at the rankings and finished year outside the top 150. In 2017, she first got recognised at the Madrid Open, where she reached semifinal alongside Simona Halep. She followed this with her first 2017 French Open quarterfinal alongside Zheng Saisai, where they lost to Ashleigh Barty and Casey Dellacqua. In July 2017, alongside Raluca Olaru, she won Bucharest Open, defeating Elise Mertens and Demi Schuurs in the final. Then, again with Olaru, she reached quarterfinal of the Cincinnati Open. At the 2017 Tianjin Open, she won title alongside Sara Errani. Unlike in 2016, she start climbing in the rankings and returned to the top 40 in October.

Singles

Begu had variable results during these three seasons. She started season of 2018 with semifinal of the Shenzhen Open, but then lost to world No. 1 Simona Halep.^[21] She then start reaching only first or second rounds, before she reached quarterfinal of the Premier-level Charleston Open in April. There she lost to Daria Kasatkina.^[5] Nearly after that she reached semifinal of the Istanbul Cup.^[22] At the Madrid Open, she defeated world No. 5 Jeļena Ostapenko in the first round,^[23] but then lost to Maria Sharapova.^[24] At the French Open, she reached third round, after defeating top 30 Zhang Shuai.^[25] In the third-round match, she was defeated by world No. 7, Caroline Garcia.^[5] She then start not doing well,^[5] but reached quarterfinals of the Korea Open in September by defeating Agnieszka Radwańska.^[26]

In the early 2019, she reached quarterfinals of the Hobart International, but then lost to Anna Karolína Schmiedlová.^[5] A month later, she reached another quarterfinal at the Hungarian Open, losing there to Markéta Vondroušová.^[27] In May, she fall out the top 100 for the first time since April 2014.^[6] Later she reached quarterfinals at the Bucharest Open, where Laura Siegemund defeated her.^[5] Her last tournament of year was the $100k Kiskút Open, where she finished a runner-up, after losing to Danka Kovinić.^[28]

Begu won the $100k Cairo Open in February 2020 defeating Lesia Tsurenko in the final. This brought her back to the top 100.^[29] She continued her good form in March and won a title on the WTA 125 Indian Wells Challenger. She did not lose a set in the entire tournament and defeated Misaki Doi in the final.^[30] In August, she reached semifinals of the Prague Open, but then lost to compatriot Simona Halep.^[31] In the first round, she defeated top 50 player Anastasija Sevastova.^[32]

Doubles

Begu started season of 2018 with a title at the Shenzhen Open, alongside Simona Halep. She done even better at the Australian Open, where she reached her first major semifinal, playing along Monica Niculescu. However, they lost to Ekaterina Makarova and Elena Vesnina. In late June, she reached the final of the Eastbourne International, but failed to win the title.^[5] At Wimbledon alongside Mihaela Buzărnescu, she lost in the quarterfinals to Nicole Melichar and Květa Peschke.^[33] She followed this up winning the title at the Bucharest Open with Andreea Mitu.^[34] In September 2018, she reached final of the Tashkent Open with Raluca Olaru, but they lost to Olga Danilović and Tamara Zidanšek.^[35] In October 2018, she reached her career-high doubles ranking of 22.^[6] In February 2019, she and Niculescu won the title at the Thailand Open, beating Anna Blinkova and Wang Yafan in the final.^[5] Later, she start producing modest results, that resulted her new dropping on the ranking.^[5][6] She continued to struggle with results and dropped out the top 100 in late January 2020.^[6] During the season of 2020, Begu won only one match, that was at the Linz Open.^[5]

Singles

Doubles