In December, a suicide bombing claimed by the IS killed 29 worshippers during Sunday mass in Cairo.
The Islamic State group claimed responsibility for a bomb attack on a Cairo church that killed 25 people, in a statement circulated on social media on Tuesday.
IS identified the suicide bomber who carried out Sunday's attack by the pseudonym Abu Abdallah al-Masri.
The bomber "got in between the crowd" and detonated his explosive belt, the jihadist group said in the statement.
The group said it would continue attacks against "every infidel and apostate in Egypt, and everywhere".
President Abdel Fattah al-Sisi named the suicide bomber as Mahmoud Shafik Mohamed Mostafa, 22, during a funeral for the victims on Monday.
Sisi said Mostafa had detonated his explosive belt at the Saint Peter and Saint Paul Church.
The interior ministry said late on Monday that Mostafa had been identified by DNA tests from body parts which matched that of his family.
The authorities have arrested four suspects, including a woman, Sisi said on Monday.
They are still searching for others, according to the interior ministry.