The tournament, to be held in southern Africa, will remain a 14-team event. However, the three lowest-ranked qualified teams will first compete in a preliminary round, with only one side advancing to the main competition.
The main stage will feature 12 teams divided into two groups of six, followed by a newly introduced "Super Seven" stage replacing the previous Super Six format.
The ICC has also scrapped the quarter-finals, meaning the tournament will move directly from the Super Seven stage to the semi-finals.
With an extra team in each group and a revised competition structure, the likelihood of Pakistan and India meeting more than once during the tournament has increased.
A Pakistan-India fixture remains the most commercially valuable match in international cricket, generating significant television audiences, sponsorship revenue and broadcast income for the ICC.
The two neighbours no longer play bilateral cricket because of longstanding political tensions and now meet only in ICC and Asian Cricket Council tournaments.
India last toured Pakistan for a bilateral Test and ODI series in 2006.
In a statement, the ICC said the new World Cup format would "create greater context, competitiveness and consequence during the event."
The ICC also confirmed changes to the format of the 2028 Men s T20 World Cup.
The tournament will continue to feature 20 teams, but 10 sides will now qualify from the group stage instead of eight.
Under the revised format, the top two teams in the Super 10 stage will qualify directly for the semi-finals, while a new eliminator round will determine the remaining two semi-finalists.
