Clegg will chair the panel, which will give independent advice on major developments affecting the built environment in the region.
It represents a significant move for Clegg, as he follows in the footsteps of his recently deceased partner Richard Feilden, who was a CABE commissioner.
The vice-chair of the new design panel will be MJ Long, senior partner of Long & Kentish, who has won plaudits for her work on the British Library in London.
'The new panel brings together a wealth of expertise in architecture and urban design,' said Clegg.
'We look forward to working with local authorities and developers in order to ensure that the region achieves the highest possible standards of design in our built environment,' he continued.
Clegg and Long will lead the panel of about 30 members drawn from all sectors of the built environment across the south west. It will meet for the first time at the beginning of October.