Daria Kasatkina, born in Togliatty where she actually resides, began playing at age six when older brother and fitness trainer, Alexsandr Timkovskii, introduced her to tennis. An avid Barcelona fan, she made her WTA qualifying debut at 2013 Moscow. Next year, at the same venue, she lost to Riske in her main draw first match at WTA level In 2014, she also she lifted the 2014 Roland Garros singles junior trophy.
In 2015 she won five singles titles on ITF Circuit in 2015, taking the total to seven, and her maiden WTA doubles title at 2015 Moscow (w/Vesnina). She reached the quarterfinals for the first time at WTA-level in Bad Gastein, as a qualifier, and reached the third round on her Grand Slam major debut at 2015 US Open (l. Mladenovic). In Moscow, she improved that performance and made her maiden semifinals showing, losing to Pavlyuchenkova having recorded the first top-20 win of her career over No.14 Suárez Navarro.
In 2016, she lost at that same stage also at Australian Open (l. eventual champion Serena Williams), Roland Garros (l. Bertens) and Wimbledon (l. Venus Williams). Other highlights of that season included reaching the second WTA semifinal in St Petersburg (l. eventual R-Up Bencic) and the quarterfinals stage in Indian Wells (l. Karolina Pliskova), Charleston (l. eventual champion Stephens having held match points), Montreal (l. Kerber), Rio Olympics (l. Keys) and Moscow (l. Goerges).
In 2017 she completed the season at No.24, up from No.27 in 2016. The campaign was highlighted by capturing her first WTA singles title in her debut final in Charleston, defeating fellow teenager Ostapenko in the first all-teenage final on tour since 2009 Linz (Wickmayer d. Kvitova). She also reached the second tour-level final in Moscow (l. Goerges).
In 2018, her first top-ten season, Kasatkina earned her best result at the majors with the quarterfinals runs at Roland Garros (l. Stephens) and Wimbledon (l. eventual champion Kerber) surpassing her previous-best R16 effort at 2017 US Open (l. Kanepi).
The Russian began the season with back-to-back first round exits at Brisbane (l. Kanepi) and Sydney (l. Strycova). Beaten in the second round in Melbourne, she reached the semifinals in St. Petersburg (l. Mladenovic). In the lasy eight she had defeated No.1 Wozniacki in straight sets to score the second career win over a reigning World No.1, becoming one of five players in WTA history to have multiple wins over World No.1s before their 21st birthday, after Venus and Serena Williams, Sharapova and Kuznetsova.
Kasatkina made her top 20 debut on February 26, 2018, at No.20. Then, she reached back-to-back finals at Dubai (l. Svitolina) and Premier Mandatory Indian Wells (l. Osaka), where she notched her fourth, fifth, sixth and seventh top 20 wins, climbing to No.11 following Indian Wells run (March 19, 2018). She fell in the quarterfinals in Charleston and Madrid. Her clay season culminated with her career-best performance at a major, when she advanced to the quarterfinals at Roland Garros (l. eventual runner-up Stephens). In Paris, she earned her sixth win over a top-two player this season when she ousted Wozniacki and, along with Sharapova, became the first Russian to reach that stage there since 2014 (Sharapova and Kuznetsova). She then matched her best major result moving to the last eight in Wimbledon (l. eventual champion Kerber).
She reached the quarterfinals or more nine times this season, and lifted the second WTA title of her career in Moscow where she recovered from a set and 6-2 4-1 down to defeat Jabeur in final. Her record improved to 2-3 in WTA singles finals, all coming at Premier-level or above.
She finished the year as the third Russian woman to debut at Hengqin Life WTA Elite Trophy in Zhuhai. She was one of the six players in the draw to pass the 40-win mark in 2018, but she failed to move beyond the round robin stage.