The campaign, created by Brave, will invite people to "tell a cheesy joke" when it airs on 20 February, ahead of Red Nose Day on 15 March.
It will run across TV, radio and online. The 20-second spot features Dixon as a judge to find the nation’s cheesiest jokes as a line of children queue up to tell her theirs.
BabyBel will run a campaign to find the cheesiest joke and the winner will get the chance to tell their joke in a national TV spot, which will air in the spring.
Entries made through the Mini Babybel website can create an animated version of themselves. The avatar then tells the joke through speech bubbles and the joke can be shared via Facebook and email.
The creative director behind the spot was Caroline Paris and it was directed by Susannah Hayes through The Virtual TV Department. Media planning and buying was handled by OMD.
Ash Bendelow, managing director at Brave said: "The campaign marries Mini Babybel’s strategic focus on creating playful experiences to the humour of Red Nose Day.
"Having Alesha acting as judge makes a simple, compelling and credible narrative for the consumer from the TV and radio right through to the digital experience."