Lemoine made her WTA Tour debut at the 2015 Brasil Tennis Cup, defeating Gaia Sanesi in the singles qualifying.

She also made her WTA Tour main-draw debut in doubles there, partnering Susanne Celik.

She won her sole WTA Tour title at the 2017 Swedish Open held in Båstad, partnering Arantxa Rus.

In the on-court television interview after the win she said that the success was even more special because the two had been friends since they were ten years old.

In July 2022, Lemoine announced her retirement with the $60k Amstelveen Open tournament playing in her home country.