She became the first player born this century, male or female, to reach the last four of a Grand Slam.
Anisimova also won her first tournament in Bogota, Colombia, becoming the youngest American to claim a WTA title since Serena Williams in 1999.
It's been a stunning rise, but she's no overnight sensation.
Her life has been completely dedicated to tennis, as it has to be in this sport.
"I started playing tournaments when I was five," Anisimova told the Herald on Sunday. "I just loved it. I was really little but I wanted to play tennis all the time. I couldn't even keep the score. I would ask my Mum, what's the score?"
Her parents are Russian, but moved to the United States in 1998. Anisimova was born three years later, and surrounded by tennis, as her older sister Maria was an aspiring player.
But Anisimova was the undoubted protégé, and soon dedicated herself to the cause.
Her potential was obvious from a young age, and she was a standout junior, winning the US Open junior title and finishing runner up at Roland Garros.
Ansimova, who signed a professional deal at the age of 14, then made an impressive transition to senior tennis and has risen more than 750 places since the start of 2017.
And there's a lot more to come.
"The French Open gave me a lot of confidence, it was a really cool experience," said Anisimova. "I think it was my breakthrough tournament, especially with some of the players I beat. Especially with the Halep match, that was one of my top matches that I have ever played. It was a really good experience for me and it is definitely motivating. I know that I play at the top level."
Anisimova won 11 consecutive sets in Paris – including a dominant 6-4 6-2 victory over former world No 1 Halep – before being stopped by Ash Barty in three sets in the semifinal.
She also made the fourth round in Melbourne, beating the 11th seed on the way, and quarter-finals in Mallorca and San Jose.
However, her life was turned upside down in August by the sudden death of her father Konstantin, who had been her coach and inspiration as a child.
She took two months off the tour, but says she never considered giving the sport away.
"No I didn't, because I love playing tennis," said Anisimova. "He was always with me on the court and he also loved it and we had goals for my career, so it is definitely something I want to accomplish things for him and for me too."
"As soon as I felt fine I was just going to be back on court and it kind of helped me cope with everything, just get the emotions out of the way and made me feel better."
Along with 15-year-old Coco Gauff, whom Anisimova beat in the Junior US Open final, Anisimova is regularly touted as the next big thing in American tennis but tries to ignore the hype.
"I don't let it get to me," said Anisimova. "I know what I want to achieve so I just focus on myself and I don't really worry what other people say."
She reached the quarter-finals at the ASB Classic last year, before losing in three sets in Viktoria Kuzmova on a notoriously windy Auckland day.
"I've been training in Miami and honestly it's been just as windy every single day so I think I've had the right preparation for this tournament," laughed Anisimova.
She will face world No 91 Kateryna Kozlova (Ukraine) in the first round.