Kadri, who led the side at the World Cup in Qatar where they beat France, made the announcement in a post-match television interview following the 0-0 draw with South Africa that confirmed their elimination.
Speaking to beIN Sports, Kadri said his contract would automatically expire since Tunisia failed to reach the semi-finals, which was the minimum requirement.
When asked if this means he has officially resigned, Kadri responded: "This is my decision and in my contract."
He was initially named as Tunisia's interim boss just days before they met Nigeria in the last-16 of the 2021 Nations Cup after then-coach Mondher Kebaier contracted COVID-19.
Kadri took over on a permanent basis following Tunisia's quarter-final elimination at the hands of Burkina Faso and guided Tunisia at the 2022 World Cup, where they failed to make it past the group stage despite pulling off a shock win over then-reigning champions France.
He offered his resignation following the tournament but the Tunisian Football Federation rejected it and instead extended his contract for 12 more months.
Kadri said he bears full responsibility for Tunisia's disappointing end to their Cup of Nations campaign.
"The defeat against Namibia in the first match affected us psychologically, and we shouldn't have lost. We improved against Mali, and today against South Africa, but we were not efficient in attack," he said.
Kadri is the sixth coaching casualty at a Cup of Nations filled with shocks as Ghana’s Chris Hughton, Algeria’s Djamel Belmadi and Jean-Louis Gasset from hosts Ivory Coast have all also been relieved of their duties.
Gambia's Tom Saintfiet resigned after his side's group stage exit and Tanzania's Adel Amrouche has been suspended by his federation after an eight-game ban was imposed on him by the Confederation of African Football for comments he made about Morocco.
