The championship bout saw Stipe Miocic defend his title against Francis Ngannou in a five round contest.
"It feels good", Miocic told WKYC.com in an exclusive interview following his UFC record third consecutive defense of the heavyweight championship.
Miocic was in control of every round all three judges went 50-44 for the undisputed star to retain his gold and smash the myth surrounding the Predator.
American Cormier, who lost the belt to Jon Jones in July 2017 but was reinstated after Jones failed a dope test in connection with that fight, landed some heavy punches in the first round and finished it on the challenger's back.
Earlier, Rob Font and Calvin Kattar had TKO wins over Thomas Almeida and Shane Burgos respectively, while Gian Villante enjoyed a split decision victory against Francimar Barroso.
With nearly no action happening inside the Octagon, Miocic flashed a straight right while Ngannou threatened with a lazy overhand right. Oezdemir tried to escape, but it was to no avail, as the unanswered barrage of blows prompted referee Kevin MacDonald to stop the fight at the 2:00 mark of the second round.
UFC 220 was a relatively successful event, all things considered.
'Khabib Nurmagomedov gets a title in a couple of months, and by the end of the year Cain Velasquez is going to be fighting for the UFC heavyweight title again.
The TD Garden was packed and lit from the opening preliminary bout and the card was sprinkled with MA fighters that sent the crowd into a frenzy with each introduction. UFC granted an immediate rematch and Razak Alhassan left no doubt about this outcome.
Oezdemir walked to the cage with his native Swiss flag draped over his shoulder to nearly no reaction from the Boston crowd.
"It's just a matter of time", said a relatively upbeat Oezdemir at the post fight press conference.
Islam Makhachev needed just one left hand and 57 seconds to knock out Gleison Tibau in the first preliminary bout.
The 31-year-old did have some success with his striking early on - as did Miocic - but it didn't take long for the champion to expose the challenger's one-dimensional skillset. Dustin Ortiz also snapped Alexandre Pantoja's 11-fight MMA winning streak dating to 2010 with a unanimous decision victory. Cormier is a minus-350 (risking $3.50 to win $1) favorite, with Oezdemir coming back at plus-270 (risking $1 to win $2.70).
UFC held its fifth card at TD Garden, the first since 2016, and the company said the arena was sold out.