Chernova showed her promise in combined events at a young age and won gold medals at the 2005 World Youth Championships in Athletics and the 2006 World Junior Championships in Athletics. In 2007 she scored a total of 6768 points – the highest score ever reached by a junior, although it is classed as wind-assisted for record purposes. On her senior global debut at the 2007 World Championships in Athletics she failed to finish the competition. She rebounded the following year at the 2008 IAAF World Indoor Championships, where she came seventh in the women's pentathlon. Later that summer she won the Hypo-Meeting in a personal best score of 6618 points and managed a performance of 6591 points at the 2008 Summer Olympics. She originally finished fourth, but following the disqualification of Lyudmyla Blonska for doping, she was upgraded to the bronze medal. She failed to build upon this in 2009 and ended the year with a season's best of 6386 points, having come eighth at the 2009 World Championships in Athletics. At the start of the 2010 season, she originally was awarded the bronze medal in the pentathlon at the 2010 IAAF World Indoor Championships, finishing behind Jessica Ennis and Nataliya Dobrynska. Chernova represented Russia at the 2010 European Athletics Championships and finished fourth in the heptathlon with 6512 points. She was the winner of the 2010 Décastar event, recording a total 6453 points, and this moved her into first place in the IAAF Combined Events Challenge rankings. Chernova began the 2011 season with a significant personal best of 6773 points at the TNT-Fortuna Meeting. This was a meeting record and represented an improvement of more than 150 points over her previous best. She had run a personal best in the 100 metres hurdles, but her consistency over all seven events proved to be the reason for the definitive improvement. in Daegu Prior to the 2011 World Championships in Athletics, it was reigning champion Jessica Ennis who was ranked number one that year, followed by Chernova. At the championships in Daegu, she equalled her bests in the 200 metres and the 100 m hurdles, and set an outright best in the shot put. On the final day, a strong performance in the javelin throw saw Chernova overhaul and establish a significant lead over second placed Ennis. She finished third in the 800 metres final, but still maintained her lead and initially became the world heptathlon champion with a personal best total of 6880 points. Chernova won the Decastar Meeting a month later to take a consecutive series win on the IAAF Challenge circuit, having amassed 20,332 points over three competitions.
Doping
After retesting of samples from the 2009 IAAF World Championships Chernova was found to have been doping. Her results from 15 August 2009 to 14 August 2011 were annulled and she was suspended for two years from 22 July 2013. On March 25, 2015, the IAAF filed an appeal with the Court of Arbitration in Lausanne, Switzerland, questioning the selective disqualification of the suspension periods of six other athletes disqualified about the same time. Chernova's case also involved strange gaps in her suspension periods, including opening up her eligibility two weeks before the World Championship gold medal and initiating another disqualification period less than two weeks after she won the Universiade gold medal. On 29 November 2016 it was announced that she had been further disqualified from all results between 15 August 2011 and 22 July 2013, including her 2011 World Championships gold and 2012 Olympics bronze. On 24 April 2017 she was disqualified and stripped of her bronze medal in 2008 Summer Olympics due to doping. This means she no longer has medals from any major championships.
