Earlier this month, news broke that Shraddha had been signed to play the female lead in the movie, which is an official adaptation of Chetan Bhagat's novel of the same name.
Arjun said he is preparing for his character and will start shooting for the film soon.
"I've committed to doing Half Girlfriend. I am prepping for it for the next two and a half months and then start it," Arjun said in an interview.
"Half Girlfriend" is a love story of a Bihari boy and an upper society girl. Based on the backdrop of how English defines a class system, it talks about Madhav, who wants a relationship with the high society, urban and English speaking Riya, but the girl is not interested in commitment. Hence she becomes his half girlfriend.
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Meanwhile, Arjun is excited as he is set to make his TV debut as the host of the new season of "Khatron Ke Khiladi".
"I was very excited when they offered me the show. I did ask them why me.. They said it's a fact that I am young enough to evolve into any format they need me to be. It was very exciting for me that they thought I was mouldable."
The actor, however, said his biggest fear was if he could host a show successfully as it is a big challenge.
The 30-year-old "Gunday" star feels Akshay took the show
to a next level as he is a true "Khiladi".
"The show is internationally renowned for its stunts. With Akshay sir coming in he took it to the next level because he is the true Khiladi.
Arjun, who has featured in action movies like "Tevar" and "Gunday", says action on TV has an "emotional thrust".
"In films, if you look scared, the director will ask for a retake. In TV, you are not playing a character, you are yourself. Films are designed, have lots of cuts, but here if you're doing a stunt it is survival of the fittest and facing your fear. It has an emotional thrust.