O’Reilly – who has more than 30 years' experience in the profession – will become the third insolvency partner at the firm.
HW Fisher partner, David Birne, hailed the capture of the former R3 president.
He said: "His appointment will strengthen and broaden HW Fisher’s insolvency team, and allow the firm to work with clients across all sectors.
"We are very much looking forward to Nick joining our busy team."
O’Reilly began his insolvency career in 1980 at the Insolvency Service before qualifying as a certified accountant in 1987.
He has previously worked for Levy Gee, which was bought by a FRP predecessor firm, before moving across to FRP Advisory, following a management buy-out in 2010.
O’Reilly, said: "I have always had a good relationship with the partners at HW Fisher and when the opportunity arose for me to join I had no hesitation in saying yes – I hope to work with the great team already in place to expand the business recovery offering at the firm."
Meanwhile, Geoff Rowley, partner at FRP Advisory added: "We have enjoyed working with Nick over many years and he moves on with our full support and best wishes for the future.
"As a growing firm we will be boosting the partner team and continuing to recruit to build our offices across the UK."
By Andy Pearce