Rapidly expanding Pelham has also poached Brunswick oil and gas expert Mark Antelme to co-head its oil and gas division alongside Alisdair Haythornthwaite.
Cornelius has enjoyed a nomadic career over the past 18 months, first joining College Hill with former Gainsborough colleague Duncan Murray last year (PRWeek, 3 February 2007).
The move led to the closure of Gainsborough but did not work out and the duo soon left.
Cornelius has since been acting as an independent consultant, but was courted by a range of City agencies.
'My role at Pelham will be to continue to grow the agency, particularly through increasing the number of FTSE 100 or 250 clients,' said Cornelius.
'I've got lots of experience in the retail sector, so I'll continue to work in that area,' he added.
Cornelius, who officially joins in July, has already been working on private equity giant Texas Pacific Group's (TPG) headline-grabbing purchase of a 23 per cent stake in ailing UK mortgage lender Bradford & Bingley. TPG is a retained Pelham client.
Antelme also joins Pelham in July. The two hires will see Pelham, not yet four years old, increase its team to 46.
Last year city and corporate veteran David Wynne-Morgan merged his agency WMC with Pelham.
The move was designed to create a consultancy with the stature to compete in the top tier of City PR (PRWeek, 14 October 2007).
Pelham was recently hired to help surfing brand Hot Tuna as its share value plummeted (PRWeek, 1 April).