The campaign will see the famous character Shaun the Sheep feature in two unique art trails.
These will include 120 giant sculptures of Shaun the Sheep, created by artists, celebrities and designers, placed in iconic locations in London this spring and Bristol during the summer.
Frank PR has been appointed to look after the London launch after a non-competitive pitch.
It is briefed with raising consumer awareness for the trail in the capital, which will take place from Saturday 28 March to Monday 25 May, as well as the trail app.
Nicola Masters, director at Wallace & Gromit Children's Charity, said: "After a hugely successful fundraising effort with the Gromit Unleashed trail in Bristol in 2013, we wanted to take our first London trail to the next level and an agency of Frank's credentials will help us reach our goals."
Andrew Bloch, founder and group managing director of Frank PR, said: "Aside from the fantastic cause and the opportunity to do some great work, we're also massive Wallace & Gromit fans – so are really excited to be briefed on this project."
When both trails are finished the sculptures will be auctioned off, with the proceeds going to support sick children in hospitals around the UK.