Smith was acting chief executive until Peter Kenyon's arrival from Manchester United two months ago, and has recently served as the club's official spokesman.
His commercially-based role will include turning Roman Abramovich's vision of rivalling Manchester United globally into reality.
Smith has already taken charge of Chelsea's planned tour of the US this summer. The tournament, in which Manchester United is also taking part, will be played in front of thousands of fans across the country and a TV audience of millions.
He is also understood to be working on advanced plans for Chelsea-branded superstores worldwide, as Manchester United has done.