Lena Ovchynnikova came to prominence as an amateur
kickboxer and
Muay Thai fighter, medaling at various national, European and world championships. She became a world champion in the professional ranks for the first time in 2009 when she won the
ISKA Women's World Super Bantamweight (56.4 kg/124 lb) Oriental Championship and the following year, she added two more world titles to her mantelpiece by winning the World Kickboxing Federation (WKF) Women's World Super Bantamweight (-56.4 kg/124 lb) belt under both kickboxing and Muay Thai rules. She challenged
Christine Theiss for her
WKA world title in
Dresden,
Germany on November 20, 2010, losing by sixth round
knockout. Ovchynnikova was then set to fight Jeri Sitzes in a match for the WBC Muaythai Women's International Bantamweight (-53.5 kg/118 lb) title in
Haikou,
China on December 18, 2010 but Sitzes withdrew for undisclosed reasons and was replaced by Li Xiao in a non-title fight. She defeated Li by
unanimous decision. Taking the place of Cong Wang who pulled out of the fight, Ovchynnikova faced professional debutant
Tiffany van Soest in
Las Vegas, Nevada,
United States on October 22, 2011, and lost by
technical knockout after retiring in her corner with a broken hand at the end of round two. Following this fight, Ovchynnikova forced herself to use only her left hand during rehabilitation which later made her ambidextrous. The pair were scheduled to rematch on July 21, 2012, in
Croatia, but it never came to fruition. Having amassed a perfect 8-0 record in
mixed martial arts, Ovchynnikova signed with the
Indian-based
Super Fight League in 2012. She tasted defeat for the first time as a mixed martial artist in her promotional debut as she
submitted to a
rear-naked choke from Sanja Sučević in round two at
SFL 1 in
Mumbai on March 11, 2012. She then lost to
Joanne Calderwood by unanimous decision at
SFL 3 in
New Delhi on May 6, 2012 in her next outing. Returning to Muay Thai, Ovchynnikova was expected to fight Emily Bearden for the
IKF women's world bantamweight (-55.4 kg/122 lb) title at
WCK Muay Thai: Nakamoto vs. Kitchen in
Pala, California, US on August 18, 2012. Her opponent was later changed to Kealani Vanderleest in a non-title affair, however, and Ovchynnikova defeated her by unanimous decision. She was then set to compete in the
Shoot Boxing World Tournament Girls S-Cup 2012 in
Tokyo,
Japan on August 25, 2012 and face
Ham Seo-Hee in the quarter-finals but was pulled from the card due to problems between
shoot boxing and Ovchynnikova's team and was replaced by
Lisa Ward. She represented the WCK Muay Thai promotion's team against a squad of Chinese fighters from Wu Lin Feng at
WCK Muay Thai: Matter of Pride in Las Vegas on November 11, 2012. Initially, her opponent was Tang Jin but was changed to Xifeng Tang. She lost by UD. In her return to SFL, Ovchynnikova beat Fathia Mostafa via submission due to a
guillotine choke at
SFL 16 in Mumbai on April 26, 2013. Back in the Muay Thai ring, she defeated Emily Bearden by UD to be crowned the International Karate Kickboxing Council (IKKC) Women's World Super Bantamweight Muay Thai Champion at
WCK Muay Thai: Hot Summer Fights in
Temecula, California, US. On January 25, 2014, she lost a
split decision to
Xiong Jingnan at
Kunlun Fight 1 in
Pattaya,
Thailand.
Bellator MMA Lena Ovchynnikova signed with Bellator MMA in 2016, going 2-2 in her first four fights in the promotion. Notably, she was the first-ever female flyweight to appear on a main card for the promotion. Ovchynnikova was expected to face
Denise Kielholtz in the co-main event of
Bellator 196 in Budapest, Hungary on April 6, 2018. However, the fight did not happen. Ovchynnikova was expected to face Kyra Batara in a strawweight bout at
Bellator 261 on June 25, 2021. However, the bout was cancelled the week of the event with one of Batara's corner testing positive for
COVID-19.{{Cite tweet|user=KyraBatara ==Championships and awards==