Each month, 700 stores will feature a poster of two missing children in the hope that shoppers will recognise them.
The online campaign will include live chat sessions with figures closely involved in missing persons campaigns. The activity will promote a dedicated UK web site set up to help missing and exploited children (www.missingkids.co.uk).
IVillage UK has also added a dedicated missing children discussion board to its site, interviews with the families of missing children and features on topics including child-snatching and support organisations.
"Tesco has been working with the police and PACT to help locate children on a regional basis, and asked us to handle the online campaign. It demonstrates the power of the internet to reach people,
said Morra Aarons, senior marketing manager at iVillage UK.
Separately, iVillage UK last week kicked off an anti-smoking campaign to coincide with National No Smoking Day.