Alice Newstead, a performance artist and former Lush employee, will have her skin pierced with shark hooks and be suspended from the ceiling to highlight how sharks are caught on longlines to be killed for their fins.
The performance will take place at 12 noon on September 3.
Lush is launching the campaign in conjunction with the to protect the world's shark population, which faces extinction due to the demand for shark fin soup and other shark products.
Lush has created a new product for the campaign, called Shark Fin Soap, which is a blue soap made with seaweed and sea salt with a cardboard shark fin sticking out the top.
It will make 11,416 bars of the soap to represent the number of sharks killed each hour, with all proceeds going to Sea Shepherd.
In each of Lush's 88 UK stores, there will be video display in the windows showing footage of sharks being pulled from the water and having their fins sliced off only to be thrown back into the ocean still alive.
As part of the campaign Lush has written to restaurants throughout the UK asking them to remove shark fin from their shelves and some retailers have already bowed to the pressure.
London restaurant Hakkasa has removed shark fin soup from the menu while Holland and Barrett has discontinued its shark cartilage capsules.
Paul Watson, Sea Shepherd's captain, said: "If we can't save the sharks, we will fail to save our oceans, and if our oceans die, civilisation and humanity will die.
"Lush and Sea Shepherd recognise that we need to save the sharks if we are to save ourselves, and we are working together to make this happen."
Andrew Butler, campaigns manager at Lush, said: "With 100m sharks being killed every year and time fast running out for the remaining 10% of the global shark population, the campaign against shark finning and longlining is perhaps our biggest challenge yet.
"We want our staff and customers to help by avoiding all shark products and supporting Sea Shepherd's vital work."