Town took an early lead through Elijah Adebayo's tenth goal of the season, but Sunderland levelled before half-time with an Amad Diallo free-kick before Trai Hume gave them the advantage heading into Tuesday's second leg at Kenilworth Road with a 63rd-minute header.
Hatters boss Rob Edwards made two changes to the side that drew at Blackburn Rovers in the penultimate league game of the season, Gabe Osho and Pelly-Ruddock Mpanzu coming in for Sonny Bradley and Luke Berry.
Tom Lockyer made his 100th Luton Town appearance as the multiple player of the year award winner returned to the side after being rested on the final day against Hull.
Berry had a place on the bench as well as Reece Burke, who played 45 minutes against Hull City on the final day after returning from injury.
Sunderland started well with the overwhelming majority of the 45,000 crowd behind them, but after a delay for Lockyer to receive treatment after being caught by an off-the-ball elbow from Joe Gelhardt, all they had to show for their bright opening ten minutes was a Patrick Roberts shot that Ethan Horvath pushed safely away from danger.
The Hatters took the lead from their first attack, Jordan Clark's low cross turned behind for a corner that he delivered himself.
Carlton Morris and Osho headed back across goal, with Alfie Doughty's close range effort turned onto the post by keeper Anthony Patterson before Adebayo turned the loose ball home to send the 2,000 Town fans up in the Gods into celebration.
Town started to control the game, and Clark produced another great bit of skill to beat his man on the right and cut-back for Adebayo midway through the half, but Black Cats defender Trai Hume threw himself in the way of the goalscorer's shot.
Adebayo had also dragged a shot wide from outside the area, while Dan Neil and Marvelous Nakamba picked up yellow cards before Luke O'Nien followed them into ref Tim Robinson's notepad for leading with an arm on Doughty, who picked himself up to bend the free-kick straight at Patterson.
Pelly-Ruddock Mpanzu was next into the book for a foul on Roberts on the edge of the Town area, and he was doubly punished as Diallo curled a beauty into the top corner from a short free-kick routine for the 39th-minute leveller.
Pierre Ekwah hit a tame shot straight at Horvath as the half drew to a close, then two minutes into the second half, Gelhardt fired wide after being set up cleverly by Alex Pritchard on the right edge of the area.
After receving more treatment, Lockyer was called upon to throw himself in the way of another Roberts shot just after the hour, before Hume headed Clarke's left-wing cross home to put the hosts in front on 63 minutes.
Diallo curled another free-kick over the bar, then Neil volleyed over from 25 yards after Ekwah's shot had been blocked on the edge of the area as Sunderland tried to make the most of their second-half dominance.
Doughty was the third Hatter to see yellow for a foul on Roberts, with the Black Cats winger rolling around having barely been touched, then Clark became the fourth before being replaced by Luke Berry with just over ten minutes to go.
Morris tried his luck from distance straight after the change, but his effort was off target, before Diallo was booked for simulation in the Town penalty area as Osho went to close him down, with the Sunderland man going to ground.
Mpanzu's shot was blocked deep into stoppage time as the Hatters remainly firmly in the tie going back to Kenilworth Road on Tuesday evening for the second leg.
TOWN: Horvath, Drameh (Onyedinma 72'), Osho, Lockyer, Bell, Doughty (Burke 88'), Nakamba, Mpanzu, Clark (Berry 79'), Morris, Adebayo.
Subs: Shea, Potts, Campbell, Freeman.
Goals: Adebayo 11'
BLACK CATS: Patterson, Roberts (Huggins 81'), Gooch, O’Nien, Diallo, Clarke, Pritchard (Ba 90+1'), Neil, Gelhardt, Hume, Ekwah.
Subs: Bass, Taylor, Lihadji, Michut, Anderson.
Goals: Diallo 39', Hume 63'
REFEREE: Tim Robinson
ATT: 46,060 (2,000 Hatters)
