For the second consecutive year, Barty began the season with a runner-up finish at the Sydney International, this time losing to Petra Kvitová.
During the event, she defeated three top 15 players, including Simona Halep for her first career victory over a current world No.
1 player.
At her next tournament, Barty made her first Grand Slam quarterfinal at the Australian Open, defeating Maria Sharapova before again losing to Kvitová.
She became the first Australian to make the quarterfinals at the event since Jelena Dokic in 2009.
After a fourth round appearance at the Indian Wells Open, Barty won the Miami Open for her first Premier Mandatory title.
She defeated three top 10 players in the event, including No.
2 Kvitová in the quarterfinals and No.
7 Karolína Plíšková in the final.
With this result, she also made her top 10 debut.

In the lead-up to the French Open, Barty played only two clay court events.
Her best result was a quarterfinal at the Madrid Open, where she lost to No.
3 Halep.
She closed out the clay court season by winning her first Grand Slam singles title at the French Open.
As the eighth seed, she defeated world No.
38 Markéta Vondroušová in the final, dropping just four games.
She only lost two sets during the tournament, one to Sofia Kenin in the fourth round and the other to Amanda Anisimova in the semifinals.
In particular, she needed to come from a set and a break down against Anisimova, after holding a 5–0 lead in the first set, to advance.
With the title, Barty became the first Australian to win the French Open in singles since Margaret Court in 1973 and the first Australian to win a Grand Slam singles title since Sam Stosur at the 2011 US Open.
She also rose to No.
2 in the world.
Barty then followed up this title with another at her next event, the Birmingham Classic, to become the No.
1 ranked player in the world.
She is the second Australian to be No.
1 in the WTA singles rankings after Evonne Goolagong Cawley.
Barty's win streak came to an end at 15 matches when she was defeated at Wimbledon by Alison Riske in the fourth round, her best result at Wimbledon to date.

Barty lost the No.
1 ranking to Naomi Osaka in early August after an opening round loss at the Canadian Open.
The following week, she fared better at the Cincinnati Open, falling to Svetlana Kuznetsova in the semifinals.
At the US Open, she was upset in the fourth round for the second time in a row at a Grand Slam tournament, this time to Wang Qiang.
Nonetheless, she regained the No.
1 ranking.
As the world No.
1 again, she rebounded during the Asian hard court season.
She reached another semifinal at the Wuhan Open followed by a runner-up finish to No.
4 Osaka at the China Open.
During the latter tournament, she defeated two top ten players in No.
7 Kvitová and No.
8 Kiki Bertens.
At the end of the season, Barty made her singles debut at the WTA Finals as the top seed.
After defeating Belinda Bencic and losing to Bertens, Barty defeated Kvitová to advance out of her group.
In the knockout round, she defeated Karolina Plíšková and Elina Svitolina, the latter of which for the first time in six attempts, to win the tour finals.
With the title, she won $4.42 million, the largest amount of prize money at a single men's or women's tournament in tennis history to date.
Barty finished the season as the year-end world No.
1.
She later won the WTA Player of the Year award, becoming the first Australian to ever receive this honour.
For the second consecutive year, Barty began the season with a runner-up finish at the Sydney International, this time losing to Petra Kvitová. During the event, she defeated three top 15 players, including Simona Halep for her first career victory over a current world No. 1 player. At her next tournament, Barty made her first Grand Slam quarterfinal at the Australian Open, defeating Maria Sharapova before again losing to Kvitová. She became the first Australian to make the quarterfinals at the event since Jelena Dokic in 2009. After a fourth round appearance at the Indian Wells Open, Barty won the Miami Open for her first Premier Mandatory title. She defeated three top 10 players in the event, including No. 2 Kvitová in the quarterfinals and No. 7 Karolína Plíšková in the final. With this result, she also made her top 10 debut.
In the lead-up to the French Open, Barty played only two clay court events. Her best result was a quarterfinal at the Madrid Open, where she lost to No. 3 Halep. She closed out the clay court season by winning her first Grand Slam singles title at the French Open. As the eighth seed, she defeated world No. 38 Markéta Vondroušová in the final, dropping just four games. She only lost two sets during the tournament, one to Sofia Kenin in the fourth round and the other to Amanda Anisimova in the semifinals. In particular, she needed to come from a set and a break down against Anisimova, after holding a 5–0 lead in the first set, to advance. With the title, Barty became the first Australian to win the French Open in singles since Margaret Court in 1973 and the first Australian to win a Grand Slam singles title since Sam Stosur at the 2011 US Open. She also rose to No. 2 in the world. Barty then followed up this title with another at her next event, the Birmingham Classic, to become the No. 1 ranked player in the world. She is the second Australian to be No. 1 in the WTA singles rankings after Evonne Goolagong Cawley. Barty's win streak came to an end at 15 matches when she was defeated at Wimbledon by Alison Riske in the fourth round, her best result at Wimbledon to date.
Barty lost the No. 1 ranking to Naomi Osaka in early August after an opening round loss at the Canadian Open. The following week, she fared better at the Cincinnati Open, falling to Svetlana Kuznetsova in the semifinals. At the US Open, she was upset in the fourth round for the second time in a row at a Grand Slam tournament, this time to Wang Qiang. Nonetheless, she regained the No. 1 ranking. As the world No. 1 again, she rebounded during the Asian hard court season. She reached another semifinal at the Wuhan Open followed by a runner-up finish to No. 4 Osaka at the China Open. During the latter tournament, she defeated two top ten players in No. 7 Kvitová and No. 8 Kiki Bertens. At the end of the season, Barty made her singles debut at the WTA Finals as the top seed. After defeating Belinda Bencic and losing to Bertens, Barty defeated Kvitová to advance out of her group. In the knockout round, she defeated Karolina Plíšková and Elina Svitolina, the latter of which for the first time in six attempts, to win the tour finals. With the title, she won $4.42 million, the largest amount of prize money at a single men's or women's tournament in tennis history to date. Barty finished the season as the year-end world No. 1. She later won the WTA Player of the Year award, becoming the first Australian to ever receive this honour.
Ashleigh Barty