Two tap-ins from Ayoze Perez, a well-worked Christian Atsu goal and a Matt Ritchie penalty, after Preston's Paul Gallagher was sent off for handling on the line just past the hour mark, warmed the crowd of 50,212 on a bitter Tyneside night.
But although Perez gave the hosts an early lead it was far from a stroll on a night of jitters and the crowd was stunned into near silence after 14 minutes when Jordan Hugill threatened to spoil the celebrations with a delightful flicked equaliser.
The goal rocked Newcastle but Atsu's strike just before the interval from a stunning counter-attack proved key and Spaniard Rafa Benitez's side kept their cool to ensure the famous old ground was rocking long before the end.
"It is brilliant," said man of the match Ritchie. "It was a little bit tense but the lads always believed.
"We are disappointed not to be top of the league but hopefully we will put Brighton under a bit of pressure by winning our next match on Friday (at Cardiff City)."
Captain Jamaal Lascelles added: "It is a bit overwhelming, to be honest. Getting back to the Premier League was always the aim and that is what we have done."
Newcastle are four points behind Brighton with two games left.
(Reporting by Neil Robinson; Editing by Ken Ferris)
