Russell was born in Ottershaw, Surrey in 1992. Russell, who has a visual impairment, took up swimming at the age of five, first joining Woking Swimming Club, before then moving to Guildford City Swimming Club at the age of twelve. She was educated at Gordon's School in West End in Surrey, before switching to Kelly College in Tavistock. In 2010, she was scouted through the 'Playground to Podium' initiative, a British system of spotting sporting talent in young people with a disability. After being classified as S12 in 2011, she entered the 2011 IPC European Championships, in Berlin. There she won two medals, silver in the 100 m backstroke and bronze in the 100 m butterfly. In 2012, she took part in the 2012 British Championships, taking another two medals, taking gold in the 100 m backstroke and silver in the 400 m freestyle. During the British Championship, Russell broke the European record in the S12 class 100 m backstroke, with a time of 1:09.52. Later that month, at the Nationwide Junior and Youth Swimming Championships in Sheffield, she broke two S12 world records, in the 400 m freestyle and the 100 m backstroke. Although stating that her sights were set on qualifying for the 2016 Summer Paralympics in Rio, Russell's results were good enough to make the Great Britain swimming team for the 2012 Games in London. At 16 years old, she was one of the youngest members of the team, and was entered into five S12 events the 50 m freestyle, 100 m freestyle, 400 m freestyle, 100 m backstroke, 100 m butterfly. In her first event, the 400 m freestyle she swam a personal best of 4:38.60 to take the silver, her first paralympic medal. She finished 0.71 seconds behind Oxana Savchenko of Russia. She won her second medal of the Games, a bronze, in the 100 m butterfly.
In 2013 Russell entered her first IPC Swimming World Championships when she travelled to Montreal as part of the Great Britain team. There she won five medals, a bronze in the 400m freestyle, three silver in the 50m freestyle, 100m freestyle and 100m butterfly and became world champion in the 100m backstroke. The following year she took part in the 2014 IPC Swimming European Championships in Eindhoven. At the games she continued her rivalry with Russian Darya Stukalova which began in Montreal. Russell won six medals, all silver, apart from the 100m backstroke for which she took gold on the day of her eighteenth birthday. Just after her eighteenth birthday, she returned to Woking Swimming Club and has had dual membership of Woking Swimming Club and City of Manchester Aquatics since May 2016. Her final major international before the 2016 Paralympics was the 2015 IPC Swimming World Championships, held in Glasgow. The 2015 Championships had a narrower list of events for S12 classification swimmers, and Russell entered only three events, winning gold in the 50m freestyle and two silver medals in the 100m backstroke and 100m freestyle.
