Harriet Dart

Dart began playing at ITF events where she beat Freya Christie, Laura Pigossi, Nastja Kolar, Conny Perrin before she reached the final of an ITF event in Germany and beat Karolína Muchová to win her first 2018 title. She reached another final in Japan but lost to Veronika Kudermetova. In Eastbourne, she won against Kristýna Plíšková before losing to then-top 10, Anastasija Sevastova.

She made her Grand Slam main draw debut at Wimbledon, as a wildcard entrant losing in the first match against former world No. 1, Karolina Plíšková in three sets. At an ITF event in Norway, she won another title; Paula Badosa retired in the final.

At the Australian Open, she lost to Maria Sharapova in the first round without winning a single game. On 30 March, Dart and her doubles partner Lesley Kerkhove won the final of the Open de Seine-et-Marne against Sarah Beth Grey and Eden Silva. At the Wimbledon Championships, Dart beat both Christina McHale and Beatriz Haddad Maia, progressing to the third round where she lost to Ashleigh Barty only winning two games. In August, Dart qualified for the US Open for the first time in her career where she lost in the first round to Ana Bogdan in straight sets.

At Wimbledon, Dart reached her first Grand Slam final making the mixed doubles decider alongside partner Joe Salisbury where they lost to Neal Skupski and Desirae Krawczyk.

Partnering Asia Muhammad, she won her first WTA 125 doubles title at the Midland Tennis Classic, defeating Peangtarn Plipuech and Aldila Sutjiadi in the final.

Dart had a breakthrough at Indian Wells. Having come through qualifying, she reached the last 16, including a win over Elina Svitolina, her first win over a top 20 player before losing to Madison Keys. The points she gained took her into the top 100 of the rankings for the first time. After a lack of success on clay, Dart entered the Nottingham Open where she defeated Donna Vekić and third seed Camila Giorgi before losing her first WTA Tour quarterfinal to sixth seed Alison Riske. She then entered the Birmingham Classic and defeated Camila Osorio, before losing to Simona Halep. At the Eastbourne International, she beat Madison Brengle, Jil Teichmann and Marta Kostyuk, before losing to Petra Kvitová in the quarterfinal. On 25 July, she rose to No. 84 in the WTA rankings, her highest ever position.

At the US Open, she secured her first top-10 win, beating Daria Kasatkina in the first round in three sets. She exited the tournament in the second round, losing to Dalma Gálfi in straight sets. In November, Dart defeated world No. 13, Paula Badosa, to help Great Britain reach the semifinals of the Billie Jean King Cup. Despite Dart overcoming Ajla Tomljanović, Great Britain lost in the last four to Australia 2–1.

In June, Dart reached successive WTA Tour quarterfinals, with runs to the last eight at the grass court events in Nottingham, where she lost to eventual champion Katie Boulter, and Birmingham, when it was Anastasia Potapova who ended her challenge. However, she could not continue her good form on the lawns of Wimbledon later that month as she went out in the first round of her home Grand Slam losing 7–6, 0–6, 4–6 to Diane Parry.

In November, Dart secured the winning point for Great Britain in their 3–1 Billie Jean King Cup play-off victory against Sweden at the Copper Box Arena in London with a 7–5, 6–2 win over Caijsa Hennemann, after being brought into the team as a late replacement for Jodie Burrage.

Dart returned to the world's top 100, after reaching her first WTA singles semifinal at the Transylvania Open defeating Anna Bondár, fifth seed Elisabetta Cocciaretto, and Nuria Párrizas Díaz, before bowing out against eventual champion Karolína Plíšková. At the same event, she also made the doubles final with partner Tereza Mihalíková.

In April, Dart was selected to play for Great Britain against France in 2024 Billie Jean King Cup qualifying round, but was not required to play as Emma Raducanu and Katie Boulter won the three matches required to qualify for the finals. Dart then won two rounds in qualifying for the Madrid Open to reach the main draw.

Alongside Diane Parry, Dart was runner-up in the doubles at the Nottingham Open, losing to top seeds Gabriela Dabrowski and Erin Routliffe in the final. At the Eastbourne International, she reached the quarterfinals before going down to a straight sets defeat against Leylah Fernandez. Dart made it through to round three at Wimbledon with victories over Bai Zhuoxuan and Katie Boulter, but then lost six games in a row from 3-0 ahead in the deciding set against Wang Xinyu to bring her run in the tournament to an end.

Dart retired due to cramp in her final qualifying match at the Canadian Open but was given a place in the main draw as a lucky loser only to be defeated in the first round by Diana Shnaider, in three sets.

She made it through qualifying at the Cincinnati Open but lost in the first round to Yulia Putintseva. Playing with Ellen Perez, Dart reached the semifinals of the doubles recording a win over second seeds Hsieh Su-wei and Elise Mertens on the way to the last four where they lost to third seeds Asia Muhammad and Erin Routliffe. This was her first appearance in a WTA 1000 doubles semifinal.

Having gained automatic qualification into the main draw through her ranking, Dart defeated Chloé Paquet in the first round at the US Open before losing to 19th seed Marta Kostyuk in round two. Despite the defeat, Dart moved into the top 70 in the Women's Tennis Association rankings. Playing with Diane Parry in the doubles, she reached the round of 16 after a three-set win over Olympic champions and sixth seeds, Sara Errani and Jasmine Paolini, in the second round. They lost to tenth seeds Chan Hao-ching and Veronika Kudermetova.

Dart reached the second round at the Japan Women's Open in October with a win over qualifier Laura Siegemund, before losing to Clara Tauson.

Wins over Lizette Cabrera and Taylah Preston saw Dart reach the final round of qualifying at the Australian Open, where she lost to Nao Hibino. However, she was handed a reprieve and entered the main draw as a lucky loser following the withdrawal of Markéta Vondroušová, and defeated Jana Fett in round one. Dart lost in the second round to 18th seed Donna Vekić in three sets.

Partnering Maia Lumsden, she reached the doubles semifinals at the Singapore Open.