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.

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.

In the qualifying for the WTA Tour event in Fes, she beat Moroccan wildcard Intissar Rassif without dropping a game.

At the WTA tournament in Seoul, Bertens defeated Vania King and Sílvia Soler Espinosa from Spain to reach the quarterfinals.

Seeded fourth for qualifying at the Paris indoor event, Bertens reached the final round where she lost to Virginie Razzano.

Bertens then earned two important wins in the Fed Cup tie against Russia, beating Ekaterina Makarova and Svetlana Kuznetsova.

At Nuremberg, Bertens won her second WTA singles title by defeating Mariana Duque Mariño in the final in straight sets.

Prior to Wimbledon, Bertens was scheduled to play at the Rosmalen Open; 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 event of the year and defeated Jeļena Ostapenko and Mona Barthel to reach the third round of the grass tournament for the first time.

Bertens ended her season at the WTA Elite Trophy where she lost both of her matches with close scorelines, against Elina Svitolina and Elena Vesnina.

She had routine wins over Annika Beck and Galina Voskoboeva in the first two rounds, but lost to qualifier and eventual champion Elise Mertens.

After a strong showing during the clay-court season, she entered the French Open and beat Ajla Tomljanović in the first round, but was upset by CiCi Bellis in the second.

After a disappointing French Open and Wimbledon, Bertens rebounded at Gstaad where she claimed the title by beating Anett Kontaveit in the final.

At the Australian Open Bertens beat Americans CiCi Bellis and Nicole Gibbs in the first two rounds before falling to world No.

The following week, she won the biggest title of her career in Cincinnati, beating top-10 players Wozniacki, Svitolina, Kvitová and Halep along the way.

[27] Bertens subsequently qualified for the WTA Finals for the first time, after Simona Halep withdrew from the tournament due to injury[28] where she reached the semifinals, losing to the eventual winner Elina Svitolina.

She reached her first final of the year in February, defeating Ysaline Bonaventure, Pavlyuchenkova and Aryna Sabalenka at the St. Petersburg Trophy.

Bertens went after a good run at Indian Wells to Miami where she reached the fourth round, after beating Wang Xiyu and Viktória Kužmová, before losing to eventual winner Ash Barty.

Bertens started off her clay-court season at the Charleston Open as defending champion and reached the third round before losing her match against Maria Sakkari, in straight sets.

However, she bounced back at the Madrid Open, where she cruised through her first three matches against Kateřina Siniaková, Jeļena Ostapenko, and Anastasija Sevastova.

She next lost in the third round of Wuhan to the defending, and eventual, champion Aryna Sabalenka, before reaching the semifinals of Beijing, defeating Donna Vekić, Dayana Yastremska, Polona Hercog, and Elina Svitolina, before losing to Ashleigh Barty.

At the WTA Elite Trophy, Bertens reached the final, defeating both Vekić and Yastremska in the group stage, and Zheng Saisai in the semifinals, before losing to Sabalenka once again.

Bertens' first tournament of the year was at Brisbane, where she defeated Dayana Yastremska and Anett Kontaveit, before falling to Naomi Osaka.

At Doha, she defeated Karolína Muchová, before losing to Zheng Saisai; this was her final tournament before the WTA Tour was suspended due to the COVID-19 pandemic.

[31] Bertens subsequently fell to another Italian player Martina Trevisan in the fourth round and announced the following month that she would undergo surgery to treat an Achilles tendon injury, sidelining her for the remainder of the season.

As she played aggressively, taking the ball early on the rise, she tended to hit large numbers of both winners and unforced errors.

Her heavy topspin forehand had the added benefit of pushing her opponents behind the baseline, forcing them to play defensively from the first stroke.

She was adept at applying slice to her backhand, which allowed her to break up the pace of baseline rallies, and draw unforced errors from more aggressive players.

[53] On retirement, Bertens reflected on her personality "From a shy little girl, with lots of fears to an independent woman who played on the biggest stages," she wrote in July.