The firm has been chosen by owner Grand Pier Ltd after it announced Bristol-based architects Angus Meek as the winner of its competition to design the third Grand Pier last month.
As part of its role, Pegasus will now liaise with North Somerset Council and the appointed task force, including English Heritage.
The proposed scheme will replace the former grade II listed pier, which suffered extensive damage during a blaze in July, and accommodate new shops and leisure facilities. Planning and listed building applications are to be submitted next month.
Pegasus director Rob Duff commented: "It is hoped that the redeveloped pier will be open to the public by the summer of 2010. It is vital that a planning application is submitted as soon as practicable and that it is determined as swiftly as possible."
Bristol office planning partner Jim Tarzey added: "It is a privilege to be involved in such a high-profile project and I look forward to the challenges it may bring."