Eddie Howe hailed Newcastle's "incredible" players as they qualified for the Champions League for the first time in 20 years after a 0-0 draw against relegation-haunted Leicester on Monday.
Fifth-placed Liverpool's draw with Aston Villa on Saturday meant Newcastle needed just one point from their last two games to be assured of a Champions League place.
Howe's third-placed side achieved their target at the first attempt at a jubilant St James' Park.
Howe and his players embarked on a lengthy lap of honour after the final whistle as they soaked up the acclaim from the Toon Army.
"It's a big relief actually, an amazing night. You always hope and you have to dream. But we didn't feel we were ready for the top four," Howe said.
"After last season's relegation battle, it was whether we could consolidate and become a better team.
"I have to compliment the whole squad because physically it's been a big demand. They've seen the fruits of their own labour."
Newcastle's remarkable rise from relegation candidates to a top-four finish in the Premier League in just 18 months is a tribute to Howe's management and financial might of the club's Saudi-backed ownership group.
The Magpies also reached the first domestic final since 1999 this season, losing to Manchester United in the League Cup.
After two decades in Premier League purgatory since Bobby Robson last led Newcastle into the Champions League, the Magpies will believe they can maintain their transformation into trophy contenders now they are back among Europe's heavyweights.
"The lads have been unbelievable for me. I can't praise them enough. Their attitude, their mentality," Howe said.
"I'm just grateful to have the opportunity to manage here. We've had great success and that's satisfying."
Just seven years after their fairytale Premier League title triumph, Leicester are on the verge of being relegated from the top-flight for the 12th time in their history.
That would equal the English record held by Birmingham, sending them back to the Championship for the first time since 2014.
Dean Smith's third from bottom team have won just one of their last 15 league games.
They sit two points behind fourth bottom Everton and will go down if the Toffees win their last game against Bournemouth, regardless of Leicester's result in their final match against West Ham.
"What we have done is taken it to the last game and made Everton need to win. That's what we had to do. I make no apologies for the way we played," Smith said.
Smith sprang a major surprise as he left James Maddison and Harvey Barnes on the bench in a bid to be "harder to beat", while Newcastle lost Joelinton to an injury suffered in the pre-match warm-up.
They nearly had to do without Joelinton's fellow Brazilian Bruno Guimaraes as well as the midfielder escaped with an early yellow card after a studs-up challenge that smashed into Boubakary Soumare's thigh.
Newcastle held 80 percent of the possession throughout the game, but Leicester sat deep to frustrate them.
Leicester keeper Daniel Iversen almost gifted Newcastle the opening goal, spilling a catch under pressure from Dan Burn.
Callum Wilson seized on the loose ball and shot against the post before his header from the rebound was cleared off the line by Wilfred Ndidi.
Newcastle hit the woodwork again moments later through Miguel Almiron's half-volley from Fabian Schaer's knock down.
Iversen misjudged another cross just before half-time, leaving Wilson with a chance that the striker headed over from close-range.
Smith sent on Maddison at the interval and Iversen partially redeemed himself with a superb save to tip over Alexander Isak's powerful drive from the edge of the area.
Guimaraes missed a sitter when he headed against the post from virtually on the goal-line after Leicester's Wout Faes accidently flicked a corner in his direction.
Leicester nearly won it with their first shot of proceedings when Nick Pope denied Timothy Castagne in stoppage-time, but Newcastle held on to clinch their return to Europe's top table.