O’Neill signed a three-year contract worth around £6million on Sunday.
He said: “It’s a very nice feeling to be back in football and to be the manager of Sunderland. It’s a very big moment for me.
“I’d heard about what a good club it was but, coming here, seeing the stadium and training ground, I’ve been bowled over. It’s absolutely fantastic.
“I hope I can help Sunderland to a very successful period. That’s what I’ve come for and that’s my driving ambition.”
O’Neill will also bring in his own staff that could add another £2-3million to Sunderland owner Ellis Short’s bill.
