The 46-year-old will star as the conservative host in the film which goes under the working title of "Rush (2014)", reported Ace Showbiz.
No further details have been revealed about the plot of the biopic.
Betty Thomas, who will serve as the director, says the production company is currently polishing the script and the production is set to kick off in 2013.
Cusack's casting as Limbaugh is quite surprising as the actor is widely known as an outspoken liberal while the radio host is famous for being a conservative.
Physically, the two also have almost nothing in common. While Cusack is slender and dark-haired, 61-year-old Limbaugh is much older, balding and portly.
Limbaugh is one of the most provocative media figures in the US. His radio show, 'The Rush Limbaugh Show', is the highest-rated talk-radio program. He is also the most-listened-to talk show host with a weekly audience of 15 million.
The Missouri-born host often sparks controversy during his on air show. Recently, he mocked Republican New Jersey Governor, Chris Christie, for having a "bromance" with Barack Obama.
