Sheff Wed will finish the year in the play-off places after a fifth win in six.
And boss Carlos Carvalhal hailed his side's performance after a vital three points.
He said: "We played absolutely fantastic.
"We kept the ball well and were a threat to Newcastle's goal all the time.
"We created clear chances to score, my players were fantastic and deserve the three points.
"I said before the game we are Sheffield Wednesday, we have a brand and we always fight for the three points.
"Newcastle's best player was their goalkeeper. He made three or four fantastic saves.
"It was an important win. We deserved the win, playing against the strongest team in the competition.
"We prepared very well for the game, we have a way to play, we have big principles and are not an easy team to play against.
"We go step by step, game by game and let's see what position we will achieve in May."