Fanning made her WTA Tour debut when given a wildcard into the singles qualifying at the Auckland Open, where she lost in the first round to Katie O'Brien.

She and fellow New Zealand junior Leela Beattie received a wildcard into the doubles, where they lost in the first round to Johanna Larsson and Jasmin Wöhr.

She and Regina Kulikova were given wildcards into the doubles, going out in the first round to the top seeds, and eventual runners-up, Julia Görges and Flavia Pennetta.

[3] Fanning scored her first ITF main-draw singles win at San Luis Potosí, Mexico, in August, where she and Anett Kontaveit won the doubles title, and reached her first quarterfinal at Bogotá the following month.

The highlight, although it didn't result in a win, was to share in the longest single game in recent history, a 39-minute marathon against Anastasia Gasanova in the second round in Incheon, Korea, at the end of May, with temperatures approaching 40 °C.

Fanning would also be in the record books for sharing in one of the longest tie-breaks of all time, losing 17–15 in the first set decider against Angelina Gabueva in the second round of qualifying for the Lexington Challenger, at the end of July.

Doubles was again Fanning's better discipline in 2019, as she reached two semifinals in Korea in May before taking her second tour title in Cairns in September with Abbie Myers as her partner, beating top seeds Maddison Inglis and Asia Muhammad in the final.

Fanning started the new year with two tournaments in Hong Kong, where she failed to qualify for the main draw in singles but reached the quarterfinals in doubles in both events.

Seeded top in the doubles with partner Erin Routliffe, the New Zealand pair were untroubled throughout the tournament, easily winning the final over Sabastiani León and Ng Man-ying.