Newcastle's Livramento sustained an injury in the weeks leading up to the tournament, but picked up a calf problem that could keep him out for up to six weeks.
Chalobah, who worked with England boss Thomas Tuchel at Chelsea, has been called upon to replace the 23-year-old, having initially been named on the standby list.
He will not join up with the squad until after the match against Croatia.
FIFA rules state that an injured or ill player can be replaced in a squad no less than 24 hours before their opening match.
The news is a blow for England, with the versatile Livramento being able to cover both right and left-back.
He played the second half of England's 1-0 warm-up win over New Zealand, but was an unused substitute for their final friendly against Costa Rica.
Chalobah has one England cap to his name and made his debut in a 3-1 defeat to Senegal in June last year.
FIFA World Cup 2026
The 2026 World Cup is taking place from June 11th to July 19th in the United States, Canada and Mexico. The tournament features 48 national teams and is played at 16 modern stadiums.
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