The 25-year-old actress starred with Kumar in Rowdy Rathore and is due to begin shooting with him again for Once Upon a Time in Mumbai 2.
The Dabangg star told PTI: "I consider myself lucky that a superstar like Akshay has shown good interest in working with a newcomer like me. He showed confidence in me when I was just one film old. He was convinced that I was the right choice for Joker and Rowdy Rathore.
"When someone as seasoned as him is confident about your acting capabilities, you do get all the more motivated. For me as an actress, it is an amazing prospect to work with Akshay. After all, not many newcomers get that opportunity and here I am doing three films with him."
Sinha also explained that Joker's sci-fi setting made the film an entirely new experience for her.
"It is really cool to be a part of such a fantastical setting. I like reading sci-fi books and watching films belonging to this genre. So when Joker came my way, it was automatically exciting.
"There were different kind of sets that were created and for me, it is a very nice and different experience when compared to the other films that I have done or am doing. The film's very uniqueness is its USP."
The film which has been described as a 'clean family entertainer', was cleared by the Indian censor board without any cuts and was awarded a U certificate.
Watch a trailer for Joker below: