Before the end of the month, Andreescu won a WTA 125K title at the Oracle Challenger Series in Newport Beach. With these three tournament results, she rose from No. 152 at the start of the year to No. 107 after the Auckland runner-up to No. 68 after the Australian Open and 125K title, a large enough ascent to become Canada's top-ranked player on the WTA Tour. Andreescu continued her hot streak with a semifinal at the Mexican Open. She then had an even larger breakthrough at the Premier Mandatory Indian Wells Open, where she won her first WTA title. Andreescu defeated four top 20 players in the last four rounds, including No. 6 Elina Svitolina and No. 8 Angelique Kerber in the semifinals and final resepctively, both in three sets. She became the first wild card women's singles champion in tournament history and was the first 18-year-old to win the event since Serena Williams in 1999. This title also took her to No. 24 in the WTA rankings. Andreescu defeated Kerber again at the Miami Open a week later. However, she then suffered a right shoulder injury in the fourth round of the event that forced her to retire from the match. Andreescu's shoulder injury kept her out of all but one tournament until August. She attempted an early comeback at the French Open, but ultimately withdrew after one match. Andreescu made her next return at her home tournament, the Canadian Open, where she won her second high-level Premier tournament of the year. She won her first four matches in straight sets, including the last two over top ten opponents in No. 5 Kiki Bertens and No. 3 Karolína Plíšková. She defeated No. 10 Serena Williams in the final, who needed to retire due to back spasms down 1–3 in the first set. With these three top ten victories, Andreescu improved her record against top ten opponents to 7–0 to open her career. With the title, she moved up to No. 14 in the world. She also became the first Canadian to win the tournament since Faye Urban in 1969. Andreescu's best result of the year came at the US Open, where she won her first Grand Slam title. She advanced to the final without facing a top-ten opponent, with her biggest wins coming against No. 19 Caroline Wozniacki in the third round and No. 12 Belinda Bencic in the semifinals.