Beterbiev (5-0) knocked down Cloud (24-3) three times in the opening round and carried the onslaught into the second, when he put the American down again with a pair of lefts to the head. Referee Michael Griffin counted Cloud out.
Beterbiev, a Russian based in Montreal, hoped to get in contention for a world title bout with a win over 32-year-old Cloud, who lost his last two bouts to world champions Bernard Hopkins and Adonis Stevenson. It was Cloud's first fight in a year, since his loss to Montreal's Stevenson in seven rounds at the Bell Centre.
Beterbiev, a two-time Olympian, was on the attack from the outset. He knocked Cloud down with four lefts and a right, then put him down with a right and again with a crushing left at the end of the first round.
In the co-feature, Dierry Jean of Montreal took down Daniel Ruiz twice with body shots in the fifth round to retain his continental NABA lightweight title on Saturday night.
Jean (27-1) dropped Ruiz with a straight left to the body, but the Mexican (32-8-2) got up and answered with a big right to the head.
Up against the ropes, Jean landed another left up the middle and Ruiz stayed down for the 10-count at 2:42 of the fifth round of the scheduled 12-round bout.
Jean's only attempt at a world title fell short with a 12-round loss to IBF champ Lamont Peterson on Jan. 25 in Washington, D.C., but began his bid for another title shot when he rebounded with a TKO win over Mario Perez in June.
The big event on the undercard was the return to the ring of 43-year-old Stephane Ouellet, the former middleweight contender who hadn't fought since a first-round knockout by Joachim Alcine 10 years ago.
The Chicoutimi, Que., fighter known as The Poet (29-6) fought with heart in the four-round bout, but was no match for 25-year-old Cedric Spera (11-0) of Belgium. Ouellet was knocked down by a left in the fourth and ended up fending off punches against the ropes with a large welt under his right eye.
Ouellet, who is best known for a pair of vicious bouts with Dave Hilton Jr. in the late 1990s that filled the Bell Centre, said he has no intention of continuing his boxing career, but joked that "my next fight will be when I'm 53."
Two more fights ended with painful liver shots
Welterweight Antonin Decarie (31-2), of Laval, Que., ended five rounds of physical, close range fighting with a left to the ribs in the fifth inning that put Ivan Pereyra (18-4) of Mexico out.
Kevin Bizier (23-1) of Mascouche, Que., still on the rebound from a loss to Ionut (JoJo) Dan in November, took down Laszlo Fazekas (21-16-1) of Hungary with a left hook to the liver only two minutes 31 seconds into their scheduled eight-round middleweight bout.
Light welterweight Junior Ulysse (4-0) of Montreal posted a unanimous decision in an entertaining six rounds over Hrystian Huczko (2-1) of Poland, and super-middleweight Erik Bazinyan (5-0) of Laval, Que. did the same to Baptiste Castegnaro (5-3) of France.
Light middleweight Steven Butler (5-0) stopped Bernard Follea (5-3-1) in the second round after knocking the Frenchman down in the first.