Alan Titchmarsh's new two-year £2m deal will include a new "peak-time gardening and lifestyle series".
This is thought to be on Friday nights and run as competition to Gardeners' World.
His return to hands-on gardening comes as ex-Gardeners' World host Monty Don returns to the BBC2 show, replacing Toby Buckland.
Charlie Dimmock and Alys Fowler are rumoured to be among those helping Titchmarsh on the gardening series.
Horticulture Week (28 January) was the first publication to report on Alan Titchmarsh's return to gardening TV.
The new contract will be the first time he has fronted a gardening show for ITV.
However the move may jeopardise Titchmarsh presenting BBC's coverage of the RHS Chelsea Flower Show, which Titchmarsh has anchored for many years.
Alongside his ITV shows, 61-year-old Titchmarsh's new deal will also cover merchandising spin-offs for the next five years.
He will host four new series of The Alan Titchmarsh Show over the next two years and further "peak-time projects", following ITV programmes such as All The Queen's Horses and Alan's Walks Of Fame.
Titchmarsh said: "This is a great opportunity for anyone involved in broadcasting, and one that I relish taking on. My greatest commitment has always been to the people at home who want reliable information put over in an easily accessible manner."
Alison Sharman, ITV director of factual and daytime, said: "Whether as a broadcaster, writer, or horticulturalist, Alan Titchmarsh is a hugely popular and talented figure in so many fields.
"His daytime show and documentary work has had huge appeal with the ITV audience and I'm delighted that we have agreed such an exciting new deal, which further develops our relationship with Alan over the coming years."