Eddie Howe’s side made history at Wembley with a superb display that left the runaway Premier League leaders shell-shocked.
Burn put Newcastle ahead late in the first half and Isak’s 27th goal in all competitions doubled their lead after the interval.
Federico Chiesa got one back in the closing seconds, but Newcastle held on for their first major silverware since the 1969 Inter-Cities Fairs Cup.
That success in the predecessor to the Europa League is a relic of a bygone era, but this long-awaited triumph will be forever etched in the memories of the Newcastle fans who turned one half of Wembley into a roiling sea of black and white with their ecstatic celebrations.
It was also Newcastle’s first major domestic prize dating back 70 years to the 1955 FA Cup.
Since the Magpies lifted the Inter-Cities Fairs Cup, 30 different English teams had won silverware, while Liverpool had clinched 38 major trophies in that time.
But after losing the 2023 League Cup final against Manchester United, Howe’s team returned to Wembley and set the record straight at last.
“We were well aware of the history and we wanted to do the club proud. We wanted to score, we wanted to perform and we wanted to win,” Howe said.
“We are breaking new ground. I thought we were magnificent today.”
Newcastle had endured five relegations to the second tier since their last trophy, with club legends like Alan Shearer, Paul Gascoigne and Malcolm MacDonald failing to win silverware in their time on Tyneside.
Aside from a brief period when Kevin Keegan’s self-styled “entertainers” challenged for the title in the 1990s, Newcastle have endured decades of underachievement and self-inflicted wounds that rendered them a laughing stock for long periods.
All that changed in 2021 when a Saudi-backed consortium completed a takeover from unpopular owner Mike Ashley and quickly hired Howe as their manager.
Thanks to Howe’s astute leadership and the Saudi financial backing, Newcastle have been transformed from relegation candidates to silverware winners.
The defeat was another painful blow for Liverpool just days after their Champions League last 16 exit on penalties against Paris Saint-Germain.
But despite failing to win their first trophy under boss Arne Slot, Liverpool still sit 12 points clear at the top of the Premier League, within touching distance of a record-equalling 20th English title.
“It’s a very disappointing result. The game went the way Newcastle wanted it. They deserved to win. We were out-played in their style. They won more aerial duels than us,” Slot said.
History for Newcastle
Liverpool are 23 points ahead of sixth-placed Newcastle in the league and hadn’t lost to them for 17 games dating back to 2015.
But Howe’s men were in no mood to be cowed by past failures
Newcastle fans unveiled a banner before kick-off urging their team to “write your name in the history books”.
They rose to the challenge in spectacular fashion, snapping into tackles and counter-attacking with purpose, while Liverpool were sluggish and sloppy in possession.
Newcastle’s desire and drive was clear to see when Joelinton tracked back from midfield to stop Jarell Quansah in his tracks and celebrated with a fist-pumping roar.
Despite nearly being caught out by Burn’s aerial prowess earlier in the game, Liverpool failed to heed the warning as the towering centre-back put Newcastle ahead in the 45th minute.
Bizarrely left unmarked, with only the diminutive Alex Mac Allister anywhere near him, Burn was allowed to rise unchallenged to meet Kieran Tripper’s corner as he thumped a powerful header into far corner from 12 yards.
Burn’s goal - Newcastle’s first in a cup final since 1976 - capped an incredible week for the journeyman centre-back, who received his first England call-up on Friday.
With Liverpool talisman Mohamed Salah completely anonymous, the lethargic Reds had no answer as Isak put Newcastle into dreamland after 52 minutes.
Newcastle dominated in the air again as Jacob Murphy met Tino Livramento’s cross with a header that found Isak, who drilled a superb first-time finish past Caoimhin Kelleher from 10 yards.
Chiesa’s stoppage-time strike set up an anxious finale, but good things comes to those who wait.
And all across Wembley, Newcastle players and fans celebrated with abandon as a party over half a century in the making got into full swing.
Forest eye Europe
Elsewhere, in the Premier Leage, third-placed Nottingham Forest have Champions League qualification for next season firmly in their sights after a 4-2 win against Ipswich in the Premier League on Saturday.
Forest’s charge towards Europe’s top club competition for the first time since 1980 continued with a dominant display at Portman Road.
The visitors struck three times in six first-half minutes to close to within four points of second-placed Arsenal and move six clear of Manchester City.
Nikola Milenkovic controlled a loose ball inside the area and blasted in on off the underside of the bar to open the floodgates.
Anthony Elanga then drilled in his first goal since Boxing Day at the end of a blistering Forest counter-attack.
Two minutes later Elanga took advantage of dreadful Ipswich defending to sprint clear and slot in his second of the afternoon.
“There is a good spell in the first half that really changed the game for six minutes,” said Forest boss Nuno Espirito Santo, who is not getting carried away dreaming of Champions League football.
“We have to focus on ourselves. Work as much as we can because there is a lot of football to be played yet.”
Jens Cajuste and George Hirst scored late consolation goals for Kieran McKenna’s men either side of Jota Silva’s fourth for Forest.
Meanwhile, Manchester City failed to ease fears of missing out on next season’s Champions League after twice blowing the lead to draw 2-2 against Brighton.
Erling Haaland and Omar Marmoush put City in front, but high-flying Brighton extended their unbeaten run to seven games thanks to Pervis Estupinan’s free-kick and an Abdukodir Khusanov own goal.
City boss Pep Guardiola said on Friday that just qualifying for the Champions League would be a “big success” after a difficult season for a side used to lifting the league title.
The English champions’ early exit from Europe’s top competition to Real Madrid had at least ensured a full week’s preparation for Guardiola’s men to bounce back from last weekend’s dismal 1-0 defeat at Forest.
Marmoush was restored to the starting line-up and proved to be City’s brightest spark going forward.
The Egyptian won the penalty from which Haaland opened the scoring with his 29th goal of the season.
City’s lead lasted only 10 minutes as Estupinan curled a free-kick in off the post past the leaden-footed Stefan Ortega in the City goal.
Marmoush blasted City back in front from long range before half-time.
Brighton, though, took just three minutes into the second half to level again when Jack Hinshelwood’s shot was turned into his own net by Khusanov.
Nico Gonzalez hit the post as City pushed in vain for a winner.
A top-five Premier League finish will almost certainly secure a Champions League place this season thanks to English clubs’ strong performances in European competition.
A point leaves City still in fifth, just one point ahead of Brighton in seventh.
“I’m always confident, in that I am a master. I do have moments when I can doubt but I find the right way, the positiveness in everything,” said Guardiola.
“I know it will be difficult for many reasons but we have nine games, nine finals.”
Arsenal beat Chelsea 1-0 thanks to a first-half Mikel Merino goal, while Manchester United compounded Leicester’s relegation fears with a comprehensive 3-0 win and Fulham overcame Tottenham 2-0.
Ipswich’s uphill task to beat the drop suffered another blow as Wolves pulled nine points clear of the bottom three with a 2-1 victory at Southampton thanks to a double from Jorgen Strand Larsen.
Paul Onuachu pulled a goal back but Southampton remain on course to post the worst ever points tally in Premier League history.
Bournemouth’s bid to qualify for Europe for the first time is fading after a 2-1 home defeat to Brentford.
Goals from Yoane Wissa and Christian Norgaard earned the Bees victory after Vitaly Janelt’s own goal had opened the scoring for Bournemouth.
Everton extended their unbeaten league run to nine games thanks to Jake O’Brien’s 90th minute equaliser in a 1-1 draw against West Ham.