[4] In the final against United States, Sasnovich first lost to CoCo Vandeweghe in the straight-sets, but then made a win over Sloane Stephens.

In September 2015, she reached her first WTA Tour singles final at the Korea Open, but lost to Irina-Camelia Begu.

Sasnovich started the season well, reaching her first Premier final at the Brisbane International,[7] where she lost against the third seed Elina Svitolina.

[8] At the Australian Open, she won against Christina McHale and Mirjana Lučić-Baroni[9] before she was stopped in the third round by eighth seed Caroline Garcia.

11, Daria Kasatkina, to reach the third round,[13] but then lost to eventual champion Naomi Osaka with a double bagel.

[14] She finished the year with a quarterfinal at the Kremlin Cup after registering a top-10 win over Kiki Bertens in the second round,[9] losing to Johanna Konta.

In the first week of the year, Sasnovich had a top-10 win over Elina Svitolina, and reached the quarterfinal, where she lost to Donna Vekić.

[16] She finished year at the Open de Limoges, a WTA Challenger event, losing to Ekaterina Alexandrova in the final.

After five months of tennis absence due to the COVID-19 pandemic,[19] she played at the Palermo Ladies Open, where she reached the quarterfinal but then lost her match to Petra Martić.

[9] After losing in the second round of the French Open in singles, she reached the quarterfinals in doubles, alongside Marta Kostyuk.

[25] As a qualifier, Sasnovich reached the final of the Melbourne Summer Set 2 where she lost to Amanda Anisimova.

[30] At the Hong Kong Open, she was runner-up in the doubles with partner Oksana Kalashnikova, losing out in the final to Tsao Chia-yi and Tang Qianhui in a match tie-break.

[31] Sasnovich reached the quarterfinals at the Jiangxi Open with wins over Viktória Hrunčáková[32] and Valeria Savinykh,[33] before losing to Leylah Fernandez.

[35] Partnering with Laura Siegemund, Sasnovich reached the semifinals of the doubles at the Dubai Championships, going out to third seeds Nicole Melichar-Martinez and Ellen Perez.

[38] After defeating Suzan Lamens in the quarterfinals[39] and Anna Karolína Schmiedlová in the last four,[40] she reached the final of the Budapest Grand Prix, losing to top seed Diana Shnaider, in straight sets.