The 31-year struck nine minutes from time to claim just the Magpies' second Barclays Premier League win in eight attempts with the game seemingly heading for stalemate.
Pardew, whose decision to replace Papiss Cisse with Ameobi 20 minutes earlier had been booed by a section of the 50,180-strong crowd at St James' Park, said: "I know the crowd weren't particularly pleased when I took Cisse, a goalscorer, off but I just felt Shola, he's a big man and this was a big occasion and he likes big occasions.
"It said QPR on the programme but really it was bigger than that, I think we all knew that and he has that calm head - he knows what is demanded here - to produce a quality goal, and it won us the game.
"I wanted to get Shola on the pitch, and thank goodness I did because it was a really class finish.
"He could have taken the shot with his right foot, which is his stronger foot, but to have that composure in that area is first-class."
Ameobi's decisive intervention came in the nick of time and was greeted by a huge sigh of relief on Tyneside after he ran on to fellow substitute Sylvain Marveaux's perfectly-weighted pass before shooting left-footed across keeper Rob Green and into the bottom corner.
It was no more than the Magpies deserved after dominating throughout but it proved a rare piece of incision with Pardew's men too often lacking craft to open up the visitors.