The ASEAN Football Federation (AFF) announced the decision Monday, saying it was done to protect players and officials, commercial partners and fans.
Originally scheduled for November 23 to December 31 this year, it was postponed due to Covid-19 concerns to April 11-May 8 next year.
Major General Khiev Sameth, AFF President, said the new dates "will provide the best opportunity for the event to be staged in its full format with home and away fixtures in both the group and knockout stages, and with stadiums filled with fans to encourage and celebrate their teams."
It will begin three days after the 31st SEA Games ends in Vietnam.
Vietnam are the reigning champions after defeating Malaysia in the final in 2018.