O’Callaghan, formerly lead partner for KPMG’s strategic and operational restructuring practice, joins from FTI Consulting where he was a senior managing director.
He has also acted as an executive director and interim CFO at a listed international retailer, and is author of Turnaround leadership: making decisions, rebuilding trust and delivering results after a crisis
The mid-tier firm has also announced the promotion of Sarah Bell to restructuring partner.
Mark Byers, global head of restructuring at Grant Thornton said, "Shaun's appointment as UK head of restructuring continues the development of Grant Thornton's specialist restructuring capability. Shaun brings important additional skills to the team at a demanding time in the economic cycle.
"His expertise will further strengthen our restructuring capabilities and enhance our position as a leading advisor on large, complex corporate restructurings.”