[4] Keys has won ten WTA Tour-level singles titles, including a major triumph at the 2025 Australian Open, where she defeated world No.

Known for a fast serve and one of the most powerful forehands in the game, Keys has used her aggressive playing style to become one of the leaders of her generation of American tennis, alongside Sloane Stephens, CoCo Vandeweghe, and Sofia Kenin.

In January 2009, she won the Copa del Café, a high-level Grade 1 tournament in Costa Rica, to become the first American winner of the girls' event in its 26-year history.

[19][20] Her best result that year was winning both the singles and doubles titles at the Grade B1 Pan American Closed ITF Championships, which is the highest level of regional tournament on the junior tour.

[21] She made her WTA Tour debut a few months later at the Ponte Vedra Beach Championships, having played in only one previous professional tournament where she lost her only match.

[27] She defeated fellow American Jill Craybas in her Grand Slam tournament debut to become the youngest match winner at the event in six years at the age of 16.

[16] At the Sydney International, Keys reached the quarterfinals of a WTA event for the first time, defeating Lucie Šafářová and Zheng Jie, the two players who had beaten her in her first two majors.

[45] During the final, she also hit a 126 miles per hour (203 km/h) serve, which would have been the fifth fastest ever on record in women's tennis history if the tournament were officially collecting serve-speed data.

Keys finished in second place in her three-person round-robin group, ahead of Zheng Saisai whom she beat and behind top overall seed Venus Williams whom she lost to in a close match.

She reached the fourth round at the Australian Open, where she lost to qualifier Zhang Shuai in a match where she was ahead up until she started to experience pain in her leg in the second set.

Despite entering the Premier-level tournament with only six wins on the season, Keys won the event after knocking out Wimbledon champion Garbiñe Muguruza in the semifinals and close friend CoCo Vandeweghe in the final in their first ever meeting.

[111] Following the US Open, Keys played in three tournaments during the Asian hardcourt season and needed to withdraw or retire from all three due to a left knee injury.

[112][113] At the WTA Elite Trophy, she advanced out of her round-robin group through the tiebreak criteria after defeating Daria Kasatkina and losing to hometown favorite Wang Qiang.

4 and reigning Wimbledon champion Simona Halep in the third round, having lost five consecutive matches against the Romanian, before defeating Venus Williams in the quarterfinals and Svetlana Kuznetsova in the final.

With a loss to Zheng Saisai and a win over Petra Martić, she finished tied for first in her round robin group, but did not advance due to the tiebreak criteria.

She defeated former Grand Slam champions, Samantha Stosur and Petra Kvitová, en route, before falling to Karolína Plíšková in a tight three-set match.

Unfortunately in the third round, after losing the first-set tiebreak and serving at 2–3 in the second set against Alizé Cornet, Keys was forced to retire from the match due to a neck injury, marking her earliest exit from the US Open since 2014, snapping a streak of five consecutive runs to the second week.

[135] Nonetheless, by virtue of reaching her fifth career Grand Slam semifinal (and her first since the 2018 US Open), she rose back inside the top 30 for the first time since August 2021 as well as equaled her match win total from the previous year.

She easily defeated Ulrikke Eikeri in straight sets before succumbing to reigning Olympic gold medalist and eventual champion Belinda Bencic in the third round.

At the Canadian Open, she reached the quarterfinals of a WTA 1000 level for the first time in doubles, partnering Sania Mirza where they defeated top seeds Elise Mertens and Veronika Kudermetova.

At the Cincinnati Open, she reached the quarterfinals defeating top seed in the third round Iga Świątek in straight sets, after five unsuccessful attempts to victory over the reigning world No.

[138][139] Next, she defeated reigning Wimbledon champion Elena Rybakina to reach her ninth career semifinal at a WTA 1000 level[140] before losing to Petra Kvitová.

[141] Playing as part of Team USA at the first edition of the United Cup, Keys won all five of her matches, defeating Marie Bouzková, Jule Niemeier, Katie Swan, Magda Linette, and Lucia Bronzetti en route to the title.

10 Danielle Collins) made her the fourth woman (after Evonne Goolagong Cawley at Wimbledon, Mary Pierce at the Australian Open, and Li Na at Roland Garros) to defeat four top-10 seeded opponents en route to a major title.

[182] Keys finally recorded her first victory against Stephens in the quarterfinals at the 2019 Volvo Car Open, winning in three sets on the way to her first career clay-court title.

[202] The Game Insight Group analyzed Australian Open data over a five-year period from 2012 to 2016 and found that Keys had the second-fastest average forehand and backhand speeds of all players.

Her fastest backhands had an average of 90.0 miles per hour (144.8 km/h), which was faster than that of Bernard Tomic and close to Nick Kyrgios, both of whom have a reputation for being able to hit powerful groundstrokes.

[206] In her early pro career, Keys also worked with two other USTA coaches, Juan Todero and Jay Gooding, who helped her break into the top 50 of the WTA rankings.

[210] Keys briefly worked with Australian David Taylor starting in June, but decided to play without a primary coach for most of the latter half of the season, including at the US Open.

[211] After a short stint with Jim Madrigal in early 2019,[107] she went back to her former coach Juan Todero and won her first clay court title in their first tournament since his return.