Nineteen primary schools in Portsmouth with a total of 3,500 pupils have so far signed up to the Walk Once a Week campaign – WoW.
Run by Portsmouth City Council, the campaign was launched at Charles Dickens Junior School, in Buckland, after similar projects in London saw 30 per cent more children walking to school.
It is hoped encouraging children to walk to schools will not only help reduce congestion on crowded city roads but also help tackle obesity.
Jackie Smith, acting head of Northern Parade Infant School, Hilsea, said her school already encouraged children to come in by other means than a car, and was happy to be taking part in the WoW campaign.
'Walking to school is healthy for children and they see more things around them,' she said.
'They learn how to behave on a road – especially crossing safely.
'It also reduces congestion and gives parents time to chat.'
At the launch yesterday, road safety officers gave out badges and talked to children about staying safe.
After school, parents also got a chance to buy high-visibility accessories for their children and talk to road safety officers.
The Portsmouth schools who have already signed up will start their WoW schemes before the half-term holidays. The council is expecting more to join in later.
Councillor Lynne Stagg, the council's cabinet member for traffic and transportation, said: 'Walking to school is great for children's health and wellbeing.
'It keeps our roads clearer and it is good for the environment.'
A survey last year found one-in-three primary school children in Portsmouth were overweight.
Each school will be given a sticker chart recording how pupils travelled to school each day and monthly results will be sent to the council's road safety team.
Prizes of high-visibility gear will go to schools where walking has increased the most, and to pupils who have taken part the most enthusiastically.