After distinguishing himself at the Siege of Belgrade in 1456, he was raised to the position of Grand Vizier as a reward, succeeding his father-in-law Zaganos Pasha.

[5] Most historians accept that Angelović was born in Novo Brdo in the Serbian Despotate, and that his father Mihailos was the son of either Alexios Angelos Philanthropenos or his son/nephew/brother Manuel, rulers of Thessaly.

[9] Dejan Djokić stated that Angelović was born "to a Serb mother and a Greek refugee father – no less than son of the last Angeloi ruler of Thessaly who had emigrated to Serbia in the late fourteenth century".

[10] Ottoman historians like Gelibolulu Mustafa Ali and later considered him as a Croat, and Angelović himself in a letter from April 1467 signed as "Abogović Hrvat" (but the Croatian ethnonym probably meant "someone from the wider south-Slavic area").

[15] Taşköprüzade (d. 1560) and Aşık Çelebi (1520–1572) name two other boys led with Angelović on horseback to Edirne, Molla Iyas and Mevlana Abdülkerim, the latter which reached the rank of kadıasker (chief judge) and şeyhülislam (Islamic scholar).

According to T. Stavrides, Angelović and his companions were educated in the palace, probably as içoğlan, and Mahmud then entered service in the Enderûn, later serving prince Mehmed, the future sultan.

After distinguishing himself at the siege of Belgrade (1456), he was raised to the position of Grand Vizier as a reward, succeeding Zaganos Pasha.

Mahmud's brother Mihailo became member of a collective regency, but he was soon deposed by the anti-Ottoman and pro-Hungarian faction in the Serbian court.

[23] According to Tursun Beg and Ibn Kemal, Angelović swam over Bojana, attacked Venetian-controlled Scutari, and plundered the surrounding area.

The cause was the suspicion that he was involved in the sudden death of Şehzade Mustafa, the favorite son of Sultan Mehmed II.