The average annual value of the contract is $1.17 million. Romanov will earn $832,500 at the NHL level in each season and the deal includes signing and performance bonuses starting in 2020-21.
The 20-year-old rearguard will join the club for training camp once his mandatory quarantine ends following his flight from Russia.
Romanov can travel to Toronto with his teammates once Phase 4 begins, but he won't be eligible for the postseason, according to Sportsnet's Eric Engels.
The move would burn the first year of Romanov's entry-level contract, Engels adds.
Montreal and Romanov agreed to a three-year contract in May, but no start date for the deal was determined due to the uncertainty surrounding the NHL season at the time.
Romanov was drafted 38th overall in 2018 and is widely considered one of the world's top defensive prospects. He registered seven points in 43 games with CSKA Moscow of the KHL this past season and was a part of the Media All-Star Team at the 2020 world juniors.
The Canadiens are scheduled to begin their play-in series versus the Pittsburgh Penguins on Aug. 1.