The interior ministry identified the attacker has been identified as 40-year-old Mamdouh Amin Mohamed Baghdady, who lived in the upper Egyptian City of Qena.
It said he was a member of a "terrorist" cell, and announced the arrest of three other members of the cell.
This is the second identification as yesterday the Ministry identified the suicide bomber responsible for the other Palm Sunday's attack that took place at Alexandria's St Mark's Cathedral.
At least 46 people were killed and more than 120 others injured in the twin bombings that hit Egypt's St George Cathedral in Tanta and St Mark's Cathedral in Alexandria on Palm Sunday.
More From This Section
The Islamic State claimed responsibility for the attacks.
The ministry said Abdallah and Baghdady were associates of Amr Saad Abbas Ibrahim, a fugitive who is the leader of a terrorist cell that orchestrated last December's deadly suicide bombing of Cairo's St Peter and St Paul's Church, which killed 29 worshipers, mostly women and children.
Egypt has seen a wave of attacks by militants since 2013 when the military toppled president Mohammed Morsi, an elected leader who hailed from the Muslim Brotherhood, and launched a crackdown against Islamists.