The activity marks the first time PHE has focused its flagship campaign on snacking.
Governments statistics show that half of children’s sugar intake comes from unhealthy snacks and sugary drinks.
The National Diet and Nutrition Survey suggests in a year the average child consumes almost 400 biscuits; more than 120 cakes, buns and pastries; around 100 portions of sweets; nearly 70 of both chocolate bars and ice creams; and more than 150 juice drink pouches and cans of fizzy drink.
The campaign will include a TV ad, created by M&C Saatchi and animated by Aardman, running for eight weeks from 2 January. This will be supported by radio, out of home, digital, social and nationwide experiential roadshows.
The Change4Life website and campaign collateral, including in-store at selected supermarkets, will offer suggestions for parents of healthier snack options, such as fresh or tinned fruit salad; chopped vegetables and lower fat hummus; plain rice cakes; crackers; malt loaf; lower fat cheese; small low-fat, lower sugar yoghurt; sugar free jelly; crumpets; and Scotch pancakes.
Parents will be given special offers on a range of healthier snacks, including fruit and vegetables at Tesco and Co-Op supermarkets. They can also sign up online for money-off vouchers.
PHE has also relaunched its Be Food Smart app as the "Food Scanner". The new app shows parents information about the calories, sugar, salt and saturated fat in food to help make choosing healthier snacks easier.
Additionally, 3.6 million leaflets will be made available to families via primary schools.
The guideline of "100 calories snacks, two a day max" applies to all snacks apart from fruit and vegetables.
Dr Alison Tedstone, chief nutritionist at PHE, said: "The true extent of children’s snacking habits is greater than the odd biscuit or chocolate bar. Children are having unhealthy snacks throughout the day and parents have told us they’re concerned.
"To make it easier for busy families, we’ve developed a simple rule of thumb to help them move towards healthier snacking – look for 100 calories snacks, two a day max."
PHE marketing director Sheila Mitchell added: "January is a key time for people to reflect on their lifestyles and is always an excellent opportunity to communicate our messages."