In 2009, she starred in the comedy film Guru En Aalu alongside Madhavan, and the thriller Passenger, sharing screen space with Dileep and Sreenivasan, respectively. While the former had an average run at the box office, the latter was declared a surprise sleeper hit in Malayalam. The film 'Passenger' in which she played the role of a television reporter 'Anuradha', became a turning point in Mamta's career.Mamta was initially approached to play the lead role in the 2009 Telugu dark fantasy "Arundathi".But she refused the offer and the movie later went on to become one of the highest grosser that year. In 2010, she worked with Jayaram in the critically acclaimed Kadha Thudarunnu directed by Sathyan Anthikkad, for which she won her first Best Actress Award from Filmfare. This film also won her the 'Vanitha award for best Actress – Malayalam', the 'Mathrubhumi award for best Actress – Malayalam' and the 'Asianet award for the best actress- Malayalam '. Other projects in 2010 included Musafir with Rahman, Anwar with Prithiviraj, and Kedi with Nagarjuna. Mamta's first film in 2011 was the Malayalam film Race, in which she played the role of Niya, wife of a cardio surgeon Abey (Kunchacko Boban). The film failed to do well at the box office. Her next release in Malayalam was Naayika. In 2012, Mamta appeared in her third Tamil film, Thadaiyara Thaakka directed by Magizh Thirumeni. In 2013 she starred in Paisa Paisa with Indrajith. In 2014 she starred in To Noora with Love in which she plays a Muslim character. She has made a comeback to Malayalam movie industry with Ranjith Shankar's Mammooty starrer "Varsham". She shared her screen space again with Dileep in "Two Countries" after doing a box office hit movie with him named "My Boss" In 2016, she starred opposite to Mammootty in Thoppil Joppan and she also signed a movie Baby sitter alongside Biju Menon. In early 2017, she signed Crossroad (2017 film) an anthology film in which she plays an orthodox Muslim. She also appeared in an extended cameo in Udaharanam Sujatha with Manju Warrier. In mid 2017,she signed Detroit Crossing aka Ranam opposite to Prithviraj and Daivame Kaithozham K.Kumarakanam alongside Jayaram but had to opt out because she did not have fresh dates to allocate for both the projects.