Bertens started the year at the Australian Open, playing the qualifications. She played in the first round against top seed Vesna Dolonts and won the first ten games before Dolonts retired. In the second round Bertens lost to Olga Savchuk in a close three-set match. The next week, in an ITF 25K event in Andrezieux-Boutheon, Bertens retired with a thigh injury in the first round against Corinna Dentoni.
She played in the Fed Cup for the Dutch team, competing in Group 1 of Europe/Africa. She partnered with Demi Schuurs in the doubles match against the Portuguese team of Bárbara Luz and Margarida Moura and won in two sets. Bertens won her singles rubber against Estonia's Eva Paalma and with Michaëlla Krajicek double-bageled Anett Kontaveit and Tatjana Vorobjova. Late February she played the qualifications for WTA tournament of Acapulco. She played Mexican wildcard Ana Paula de la Peña in the first round and won but lost in the second qualification round to Sesil Karatantcheva.
At an ITF 25K event in Irapuato, Mexico, Bertens won her second ITF singles title, beating Kazakh Yaroslava Shvedova in the final, bringing her to a new career high in singles ranking. The following week, she made it to the quarterfinals of the 25K tournament in Poza Rica, but her winning streak was ended by Jana Čepelová. At the 25K tournament in Bath the week afterwards, Bertens won the title, defeating Annika Beck in the final in three sets, her fourth three-set match in a row. Bertens failed to qualify for the WTA tournament in Copenhagen, going down to Johanna Konta.
At the qualifying for the WTA tournament in Fes, she beat Moroccan wildcard Intissar Rassif without losing a game. She reached her first WTA final in this tournament, defeating Urszula Radwańska, no. 6 seed Chanelle Scheepers, Garbiñe Muguruza, and no. 5 seed Simona Halep along the way. Before the tournament she never won a WTA singles match in the main tournament. In the final she defeated Laura Pous Tió, winning the last eight games. She became the first Dutch female player since Michaëlla Krajicek in 2006 to win a WTA singles tournament.
At the French Open, Bertens was seeded No. 1 in qualifying and defeated Annika Beck in the first qualifying round, saving a matchpoint in the third set. She defeated Olga Puchkova in the second round and outclassed Mădălina Gojnea in the final qualifying round. This meant Bertens' first main draw appearance at a Grand Slam tournament. In the first round she lost in three sets to Christina McHale.
Bertens debuted at Wimbledon in her first round match against the Czech no. 19 seed Lucie Šafářová and won in two sets, her first win at a Grand Slam event. In the second round she lost to Yaroslava Shvedova in straight sets. Bertens then made a brief appearance at the ITF tournament in Biella, but lost to homeplayer Nastassja Burnett in the first round. This was followed by first round losses in Palermo and Båstad to Alexandra Cadanțu and Polona Hercog respectively.
Bertens returned to form during the American hardcourt circuit. In Montreal, she qualified by defeating Vladimíra Uhlířová, Zhang Shuai, saving two matchpoints, and Alexa Glatch. In the main draw, Bertens caused an upset, defeating former world no. 3 and world number 22 Nadia Petrova, coming back from a 3–6, 1–4 deficit. In the second round Caroline Wozniacki proved too strong, and Bertens lost in straight sets. As well as in Montreal, Bertens managed to qualify for the main draw in Cincinnati, defeating Aravane Rezaï and Yulia Putintseva. However, in the main draw she succumbed to fellow qualifier Sesil Karatantcheva. Her next tournament was in Dallas, where she retired with a shoulder injury against Polona Hercog.
At the US Open, Bertens managed to get revenge on Christina McHale, knocking out the American in the first round but suffered a three-sets loss to Russian Olga Puchkova in the second round and said afterwards she was nervous during the match. At the WTA tournament in Seoul, Bertens defeated Vania King and Sílvia Soler Espinosa from Spain to reach the quarterfinals. She faced Estonian Kaia Kanepi next and lost in straight sets. After a second round appearance in Linz she ended her season with a first round loss in Luxembourg due to fatigue.
Bertens started the year ranked No. 63. Her first tournament was the 2013 ASB Classic. In the 1st round, she defeated Svetlana Kuznetsova 6-7(5), 6-2, 7-5. In the 2nd round, she beat Heather Watson 6-4, 3-6, 6-3. In the quarterfinals, Bertens was defeated by Jamie Hampton 6-1, 6-7(5), 6-2. Seeded 5th for qualifying at the 2013 Apia International Sydney, Bertens lost in the 1st round of qualifying to Misaki Doi 6-3, 6-0. Ranked 60 at the 2013 Australian Open, Bertens was defeated in the 1st round by Lucie Hradecká 6-2, 7-6(8).
Seeded 4th for qualifying at the 2013 Open GDF Suez, Bertens reached the final round of qualifying where she lost to Virginie Razzano 2-6, 6-2, 6-1. However, Bertens got a spot in the main draw as a Lucky Loser. She reached the semifinals after wins over Tamira Paszek, 4th seed Dominika Cibulková, and 6th seed Lucie Šafářová. In the semifinals, Bertens faced top seed Sara Errani. Errani led 5-0 in the 1st set when Bertens retired due to a back injury.
At the 2014 French Open she reached the fourth round as a qualifier in which she was defeated in three sets by Andrea Petkovic.
In 2015, she changed coaches from Christiaan de Jong to Raemon Sluiter.
Bertens started her year in Auckland, where she entered the main draw as a qualifier. She lost in the first round to Barbora Strycova. At the Hobart International, she reached the quarterfinal, losing there to Dominika Cibulkova. She lost in the first round of the Australian Open to Laura Siegemund.
Bertens then earned two important wins in Netherlands' Fed Cup tie against Russia, beating Ekaterina Makarova and Svetlana Kuznetsova. They ended up beating the 2015 finalists. After that, Bertens had early defeats in Acapulco (losing to Naomi Osaka in the first round) and in Monterrey (losing in the last round of the qualifying to Pauline Parmentier). After entering Indian Wells' main draw as a qualifier, she lost in the first round to Coco Vandeweghe. Prior to the Miami Open, she played at the San Antonio Open where she reached the round of 16. Then, in Miami, she once again reached the main draw through qualifying and earned wins over Saisai Zheng and No.25 seed Anastasia Pavlyuchenkova before retiring in the third set in her third-round match against Angelique Kerber.
Playing for Netherlands at the Fed Cup semis against France, Bertens kept her winning streak by beating Caroline Garcia and Kristina Mladenovic, both in straight sets; nonetheless, it was not enough as France won the tie in the doubles decider. After that, she started her clay season with a semifinals run in Rabat, only losing to Marina Erakovic.
At Nuremberg, Bertens won her second WTA singles title after defeating Mariana Duque Mariño in the final in straight sets. In the second round she had defeated top-seeded Roberta Vinci which was her first win against a top-10 player. It was her first title since 2012. She also won the doubles title alongside Johanna Larsson.
At the French Open, Bertens avenged her Miami loss by upsetting No.3 seed Angelique Kerber in three sets. She then beat Camila Giorgi, No.29 seed Daria Kasatkina, No.15 seed Madison Keys and No.8 seed Timea Bacsinszky en route to her first Grand Slam semifinal. In her semifinal match against the No. 1 seed Serena Williams, Kiki played with a left calf injury which made it difficult for her to move forward to Williams drop shots. Bertens never took advantage of a medical time out or took trainer treatment. Despite having two set points and being up by a break in both sets, she lost in straight sets. However, she entered the top 30 for the first time in her career.
Prior to Wimbledon, Bertens was scheduled to play at the Ricoh Open; however, due to the same injury that harmed her left calf, she was forced to pull out of the tournament. After a few weeks of recovery, Bertens kicked off her campaign at the third Grand Slam of the year and defeated Jelena Ostapenko and Mona Barthel to reach the third round of the tournament for the first time. She then lost to Simona Halep.
Her next tournament was the inaugural Ladies Championship Gstaad, where she reached the final. She lost one set to Tamira Paszek en route. In the final, Bertens lost in three sets to Viktorija Golubic. Despite the defeat, she climbed to No.21 in the rankings.
Despite winning her second title of her career this year and making it to the semifinals of the French Open, Bertens lost in the first round of six straight tournaments, notably including the 2016 Summer Olympics and 2016 US Open. As a result of her inconsistency, she decided not to compete at the 2016 Wuhan Open and 2016 China Open. She made her return at the 2016 Linz Open. However, she lost in the first round to Sorana Cîrstea. Despite this, Bertens won the doubles with Johanna Larsson. Her next event was the 2016 Luxembourg Open. She had her best result since Wimbledon by making it to the semifinals, losing to Monica Niculescu. However, she did not go home empty handed. Bertens and Johanna Larsson won their second doubles title in a row. Bertens ended her season with at the 2016 WTA Elite Trophy where she lost both of her matches with close scorelines, against Elina Svitolina and Elena Vesnina.
Bertens started her year off with a first round loss to Lauren Davis at the 2017 ASB Classic. However, Bertens and Johanna Larsson won the doubles title. She was seeded first at the 2017 Hobart International. Kiki had routine wins over Annika Beck and Galina Voskoboeva in the first two rounds, but lost to qualifier and eventual champion Elise Mertens. Bertens continued to struggle during her next four tournaments. She lost in the first round of all of them including the 2017 Australian Open.
Bertens then traveled to the United States for the 2017 Indian Wells and 2017 Miami Open. She lost to Timea Bacsinszky at Indian Wells in a hard fought three setter. Bertens lost in the second round in Miami to qualifier Risa Ozaki.
Bertens had a strong start to her clay court season. She made it to the third round of both the 2017 Volvo Open and the 2017 Copa Solsanitas. Bertens lost in the first round of the 2017 Porsche Open. However, she made it to the quarterfinals of the 2017 Madrid Open. She beat former top ten players Ekaterina Makarova and Timea Bacsinszky along the way before losing to Anastasija Sevastova. She had an even more impressive journey during the 2017 Italian Open. She made it to the semifinals, but lost to Simona Halep. Bertens entered the 2017 Nuremberg Cup as the defending champion. She successfully able to defend her title by defeating Barbora Krejčíková in the final, 6–2, 6–1. This was her third career singles title.
In the 2017 Ladies Championship Gstaad in Gstaad, Bertens claimed the title by beating Anett Kontaveit. She also claimed the doubles title alongside Johanna Larsson.
Bertens is currently competing at the 2017 French Open. She beat Ajla Tomljanović in the first round and lost to CiCi Bellis in the second round.
Bertens was defeated in the first round of the 2017 US Open by Maria Sakkari 6-3, 6-4.
Only results in WTA Tour main draw (incl. Grand Slams), Olympic Games and Fed Cup World Group are included in Win–Loss records.
Levels of Fed Cup in which Netherlands did not compete in a particular year are marked "Not Participating" or "NP".