Nisha, who is also a popular face in southern film world, will marry Mumbai-based businessman Karan Valecha Dec 28.
"My beloved little sister has grown up to choose a partner for herself. She is getting married on Dec 28 in Bombay. This is going to be the biggest and most emotional day for me and my family," posted Kajal on her Facebook wall.
Kajal, who is currently on a break with her family, finished all her pending work for "Jilla" one week in advance.
"She had told me about her sister's wedding and that she should be with her a few weeks in advance. We, therefore, completed her portion quickly and ensured she has ample time to spend with her family," the film's director Nesan told IANS.
Post wedding, Nisha is likely to continue with her acting career.
"I will most likely continue working. I haven't thought about leaving the industry yet and moreover Karan is fine with me doing what I have been doing. I will probably choose roles with some care henceforth," Nisha had earlier told IANS.
The 24-year old actress is awaiting the release of her Telugu romantic-action "DK Bose".