The co-writer of Adele's Set Fire To The Rain and Taio Cruz's Break Your Heart told Music Week that, while other producers were working on what will be in Glassheart her third studio set, he was taking a production role for the whole album as well as co-authoring about half its tracks.
This approach is entirely different to Lewis's first two albums Spirit and Echo, which were littered with different songwriters and producers across their tracks, among them Max Martin, Dr Luke, Stargate, Ryan Tedder and Steve Mac.
Smith suggested having one producer overseeing everything would result in Lewis "making an artist album rather than it being a collection of songs".
When having a mixture of producers for one album he reckoned "you end up with maybe two or three radio songs and not necessarily the album sales you want".
"It's been amazing," he said. "It's been a great challenge to come up with a vision at the beginning of how we wanted it to sound and I hope to be able to do more projects like that in the future."
"People have preconceptions of what Leona is so you want to keep the essence of that and keep pushing the boundaries," added Smith who is signed to Sony/ATV Music Publishing.
He revealed the Syco album, which has been given a release date of November 26, was now about 80% finished. "We've got the key tracks and we're very close. She's done some fantastic vocals and is making a very relevant record and a very important record for her. The songs are really strong," he said.
Smith, who is currently in the studio with Dappy, also met The Voice finalist Tyler James last week and is very keen to collaborate with him.
"He's fantastic," he said of the will.i.am protegee. "His journey is interesting and he is so ready for stardom now more than ever. Having been an artist in the past and having had that success and that real rollercoaster ride of the past few years he's ready to make an exciting album."
Smith described Tyler, whose career is being overseen by the Black Eyed Peas co-founder, as a modern day Maxwell and Terence Trent D'Arby and believed he typified The Voice's values.
"He's got a unique voice," he said. "It's what the programme is all about. It's about the voice, but also finding stars."