Juicy Drink, made with 75% pure juice and 25% spring water, will be available in five-packs of 200ml cartons in orange and apple flavour (rsp: £2.99).
The products will be rolling out across the multiples later this month.
Mumsnet acted as a sounding board during the development of the drinks, said Innocent marketing director Thomas Delabriere.
"Some 58% of mums say they occasionally add water to the juice they give to kids," he said.
"You can do that for your kids at home but when it comes to lunchboxes, we think this product offers a unique solution."