Jenas, who recently completed a £5million switch from first division Nottingham Forest, didn't look out of place as his first start coincided with his first Tyne-Wear derby.
"I thought he did very well, he has good feet, he didn't panic, and he lasted the game," said Robson.
"He is 19, he hasn't developed his full game yet, and is not mature or 100 per cent, but he had nice touches and didn't lose the ball.
"He competed, and he stayed with people.
"I never, ever thought about taking him off, to be honest.
"He has savoured his first big Premiership game and we have won at Sunderland, where there is no bigger place to make a debut and no bigger place to get a victory in, so I think he is absolutely on cloud nine."