Singh trained as a Kickboxer and as a mixed martial Artist from her childhood, under the guidance of her father. She made her debut in a national competition by competing in the 52 kg category at the 2009 Asian Indoor Games as a kick boxer. She subsequently appeared in the inaugural season of the Super Fight League and competed as a mixed martial Artist. she played worldwide and won the game with an Egypt girl.
In 2013, Singh was spotted by Director Sudha Kongara Prasad in an advert for the Super Fight League and was later auditioned to play a leading role in her bilingual film, Saala Khadoos (2016), after the makers managed to contact her through the competition's chairman, Raj Kundra. Portraying Madhi, a Marwari girl who grows up in the slums of Chennai, Singh was signed because the makers wanted a professional boxer to act, rather than an Actress to act as a boxer. For the Tamil version, Irudhi Suttru, Singh phonetically learned her part in Tamil by writing down the dialogues in Hindi. Co-produced by the film's lead actor R. Madhavan and Rajkumar Hirani, the film was released in late January 2016. Ritika received rave reviews for her portrayal, with Sify.com stating "she is a marvelous discovery" and "her lip sync, body language and gait is a major highlight for the film". For her performance in Irudhi Suttru, Ritika won the a Special Mention at the 63rd National Film Awards, and became the first Actress, who did not dub for her role, to be recognised at the National Awards. Singh later appeared in Manikandan's Aandavan Kattalai, which was released in September 2016.
As of September 2016, Singh is working on P. Vasu's Shivalinga and Guru, the Telugu remake of Irudhi Suttru.
