She made her motion picture debut in the 1999 Hindi-language comedy film Haseena Maan Jaayegi which was released in June 1999, grossing INR 27 crores worldwide.

[citation needed] Thackeray first worked at the Centuar Hotel where she handled administrative and managerial tasks for a small stipend.

Smita Thackeray's aim in setting up Mukkti Foundation was to raise awareness about HIV and AIDS[8] and to abate youth drug abuse.

In 2003, three public service announcements[11] were produced starring celebrities such as Amitabh Bachchan, Waheeda Rehman and Akshay Kumar.

[12] In December 2018, Smita Thackeray, along with stars Sunny Leone, Nisha Harale, Rohit Verma headed a "Freedom Parade" in solidarity with the LGBT community.

[15] Smita Thackeray in 2001 was elected as the first female president of Indian Motion Picture Producers' Association (IMPPA).

[17][18] For the first time in the history of IMPPA, a fundraiser was hosted by the association called Ehsaas 2002 to raise funds for medical and education centres for spot boys and light men.