The pair have been spotted spending time together in New York City and also attended a 'haunted hayride' in Los Angeles last week, reports New York Post.
© WENN / B.Dowling
© WENN / FayesVision
An informant said of the romance: "They have been seeing each other for a little over a month, but things are going well."
Representatives for Franco and Benson have not commented on the dating rumour.
Franco has dated Hollywood actresses in the past, including a five-year relationship with Whatever it Takes co-star Marla Sokoloff.
He next stars with Mila Kunis and Rachel Weisz in Oz: The Great and Powerful, opening on March 8, 2013 in the US and the UK.
Watch a trailer for Oz: The Great and Powerful below:
