Jung (13-3) drove Poirier back to the fence with an uppercut and a left early in the fourth round, then hurt him with a big flying knee. Poirier tried to fight back with a takedown but the South Korean grabbed his neck and rolled into a D'Arce choke.
Referee Dan Miragliotta stepped in at one minute seven seconds of the fourth round.
The 23-year-old Poirier (12-2) had won five straight including all four previous outings in the UFC. But Jung had too much for him.
"I want Jose Aldo," Jung said in English after the fight, referring to the featherweight champion.
He will have to wait his turn. Aldo is set to fight Erik Koch at UFC 149 in Calgary on July 21.
The 25-year-old Korean was coming off a 6.2-second knockout of Canadian Mark (The Machine) Hominick at UFC 140 in Toronto last December.
Jung tripped Poirier at the fence in the first round and cut him him with an elbow. Poirier reversed position but the Korean got back up and the two finished the round swinging.
The Korean caught a kick early in the second and threw Poirier down, scoring with some blows from above. Poirier was hurt by a flying knee at the fence and then, after trying to launch a takedown, found himself mounted by the Korean.
Jung looked for an armbar and then triangle, hammering away with elbows at Poirier's head. But the fighter from Louisiana somehow escaped and rolled into top position. The bell saved Poirier from a triangle choke.
Poirier began to find his range in the third, only to be taken down midway through the round. Poirier got back up but the Korean scored points. Both men exchanged blows at the fence with Jung showing damage around the face.
In the co-main event at the Patriot Center, welterweight Amir Sadollah won a split (29-28, 29-28, 28-29) decision over Jorge Lopez in a fight contested mainly in the clinch at the fence.
Sadollah, winner of Season 7 of "The Ultimate Fighter," improved to 7-3 while Lopez fell to 11-3.
Canadians went 2-1 on the night.
(Filthy) Tom Lawlor celebrated his 29th birthday by stopping Canadian middleweight Jason (The Athlete) MacDonald in the first round.
Lawlor (8-4 with one no contest) stunned MacDonald with a left to the face and then clipped him on the side of the head with a right that sent the Canadian face down to the canvas. Lawlor got one more punch in before the referee stepped in after just 50 seconds.
"I feel good, I'm elated," said Lawlor.
MacDonald (26-16) was bidding for a win to secure one final fight —at UFC 149 in Calgary. But he failed in an early takedown attempt and lost the standup war dropping his UFC record to 6-8.
The 36-year-old from Red Deer, Alta., was giving up seven years to Lawlor but had a six-inch reach advantage. At six foot three, he also had a three-inch edge in height.
Earlier, Canadian lightweight T.J. Grant won a unanimous 30-27 decision over Carlo Prater. For the 28-year-old from Cole Harbour, N.S., it marked the first time he had put back-to-back wins in the UFC together.
"It means a lot. It's tough when you win one, lose one but this is my career and I want to succeed — I want to fight the best," said Grant, who upped his record in the UFC to 5-3. "This is a step in the right direction for me and I'm thrilled to get the win tonight over a tough guy."
Montreal bantamweight Yves (Tiger) Jabouin dominated a game Jeff (Hellbound) Hougland to win a unanimous (30-27, 30-26, 30-27) decision.
Jabouin crumpled Hougland (10-5) with a spinning back kick late to the midsection in the first round, sending him flying backwards to the ground near the fence. The American seemed reluctant at first to continue but regained his sense and survived the final 50 seconds.
"Once that back kick sits in, not a lot of guys can withstand it. He took it like a man, my hat's off to him," said Jabouin.
"Probably the toughest guy I've ever faced. I tried everything on this guy, everything in my arsenal," he added.
Hougland, a black belt in Brazilian jiu-jitsu, tried for several takedowns in the second round but the faster Jabouin danced away. Jabouin put Hougland down several times in the third but could not put him away.
Jabouin (18-7) had welterweight champion Georges St-Pierre in his corner.
Lightweight Donald (Cowboy) Cerrone used his height, reach and kicks to punish Jeremy Stephens en route to a 30-27 unanimous decision.
Stephens (20-8), an injury replacement for Yves Edwards, was cut around the left eye in the first and never found a way to get close enough to Cerrone to use his power. He did manage to cut Cerrone on the top of the head twice with elbows from the bottom when the fight went to the ground in the second round.
Cerrone (18-4 with one no contest) looked very impressive in rebounding from a lopsided loss to Nick Diaz. He has now won five of six in the UFC.
Croatian light-heavyweight Igor Pokrajac won a unanimous (29-28, 30-27, 29-28)decision over Brazil's Fabio Maldonado in a fight that could have gone either way and saw neither man yield an inch.
Pokrajac (25-8) spent most of the first half of the round on top of Maldonado but the former Brazilian boxer got up and punished him with strikes.
In the second round, Maldonado (18-5) looked to attack with knees from the Thai clinch but the Brazilian made the hard-headed Croatian pay with savage body shots.
It was more of the same in the third with Pokrajac showing some power of his own.
"That was a WAR!!!! Props to both guys," tweeted UFC president Dana White.