The Black Cats boss is delighted with the young Irish winger and paid tribute to his side who have claimed an impressive 22 of the last 30 points available in the league
The 22-year-old Irishman joined the Black Cats last summer from Derry City for a fee of just £350,000 and since O’Neill’s arrival at the club he has produced a number of impressive performances.
He scored his third goal of the season with a fantastic solo effort to give his side a 1-0 victory against Stoke at the Britannia Stadium on Saturday.
McClean made his debut in O’Neill’s first game in charge for the club in a win against Blackburn, and his displays have led many to believe he will be given a chance at international level by Republic of Ireland manager Giovanni Trapattoni.
"He is performing brilliantly for us," the Sunderland boss told reporters.
"He has had a great, great couple of months. Considering everything, I thought he took his goal brilliantly.
"I didn't know him at all until I arrived at the football club, so to see him blossoming out there has been very pleasing for everyone, obviously myself included."
Sunderland have won eight of their twelve games since O’Neill has arrived at the club and their fine form has seen them move up to eighth place in the Premier League table.
The former Celtic and Aston Villa manger is understandably delighted at the run his team have been on which has seen them collect 22 points from the last 30 available, and paid tribute to the confidence his side have found.
"It has been a great, great run and more points than we could have imagined at the start of December. With the way results were, it has been very important for us.
"The players are playing with confidence and good self-belief and that is all you can ask for."