Lego is the first brand to sponsor the entire children's offering, which includes Teenage Mutant Ninja Turtles, Curious George, SpongeBob SquarePants and My Parents are Aliens.
The deal will run during the autumn schedule until Christmas. Lego will also advertise on the CiTV website.
Clare Cullinane, Lego brand manager, said: 'Our sponsorship of CiTV gives us the opportunity to be front-of-mind with our audience during the most important buying period.'
The deal was negotiated by Carat Sponsorship and ITV Sales; the idents have been created by Iris.
The agreement comes at a vital time for the children's television industry, which is preparing itself for the tightening of regulations governing advertising of food and drink to children.
Ofcom has estimated that a ban on junk-food ads before the watershed could cost ITV 4.2% and Five 3.1% of total advertising revenues.
A ban could wipe out all investment in original UK children's programming from the commercial sector, according to the producer's industry body, Pact.
Earlier this month it was revealed that ITV is in discussions with Ofcom to drop children's shows from the daytime schedule of ITV1. Its children's programming attracts only about 8% of the available audience.