Olivia Ann Nicholls (born 26 October 1994) is a British tennis player who specializes in doubles. On 28 October 2024, she peaked at world No. 38 in the WTA doubles rankings.
Nicholls has won two doubles titles on the WTA Tour, one doubles title on the WTA Challenger Tour and 19 doubles titles on the ITF Circuit.
At the 2017 Summer Universiade held in Taipei, Taiwan, she won the bronze medal in women's doubles, along with Emily Arbuthnott.
She made her WTA Tour debut at 2022 Lyon Open in the doubles draw, partnering with Alicia Barnett. The duo finished runners-up, losing to Laura Siegemund and Vera Zvonareva in straight sets. Nicholls and Barnett won the doubles title at the Championnats Banque Nationale de Granby, defeating Harriet Dart and Rosalie van der Hoek in the final which went to a deciding champions tiebreak.
At the 2023 Wimbledon Championships, partnering with Jonny O'Mara, Nicholls reached the semifinals in the mixed doubles, losing out to eventual champions Mate Pavić and Lyudmyla Kichenok.
Alongside Olivia Gadecki, Nicholls won the doubles title at the ATX Open, defeating Katarzyna Kawa and Bibiane Schoofs in the final.
Prior to the 2024 US Open, where she reached the third round for the first time with new partner Tereza Mihalikova, Nicolls reached a ranking of No. 57 on 19 August 2024, making her the No. 1 British female doubles player ahead of Heather Watson.
Nicholls and Mihalikova reached back-to-back quarterfinals at the China Open and at the next WTA 1000, the Euhan Open.