Leftfield Entertainment makes programmes such as Real Housewives of New Jersey, American Restoration and Pawn Stars.
According to ITV the deal, for an 80% stake, will be earnings enhancing from day one.
The transaction also allows for ITV to buy the remainder of the stock three to five years from now for a maximum consideration of around £450m. The upper price would only become payable if Leftfield delivers average earnings before interest, tax, depreciation and amortisation (EBITDA) of $130m (£77m) between years three and five.
The company was said to have delivered $38m EBITDA in 2013.
Leftfield owner and chief executive Brent Montgomery is staying on to run the business.
Mr Crozier said: "Leftfield is a fantastic success story, rapidly growing from a single pilot to become one of the biggest [independent producers] in the US.
"The team has combined creativity with strong production expertise, with over 70% of the business coming from returning series and a pipeline of new ideas coming through in 2014 and into 2015 that is really encouraging."
In recent years ITV has bought US based Gurney Productions, Thinkfactory Media and High Noon as well as UK production houses The Garden and Big Talk.
It has also scored international drama hits with the likes of Downton Abbey and Mr Selfridge.
Separately, STV has taken on Sarah Brown from the BBC to be its new head of drama.
Ms Brown has worked on programmes such as Lark Rise to Candleford and Oliver Twist.