Destined to become "the leading intellectual of his generation in Siam", in the words of the Thai historian David K. Wyatt (cited in Reynolds 1979:xiii), his royal name was Prince Manuṣyanāgamānob (พระองค์เจ้ามนุษยนาคมานพ) ('he who is a nāga among men').

He was then fostered by a maternal relative, Princess Varaseṭhasutā or "Putrī", a daughter of King Rama III, and her mother, a royal concubine named Samaśakti or "Ueng".

The nobleman Phraya Pariyatidharrmadhātā or "Piam" (then called Luang Rājābhirama), deputy head of the Royal Pundits Department, came to the Palace to teach the young Vajirañana and other princes the Khmer script used to inscribe religious texts in Pāli.

With a teacher who was official at the Outer Court, Vajirañana studied Padamālā (Pāli grammar), the Dhammapada commentary, and other texts until 1868.

There he occasionally studied Pāli scripture with Phra Pariyatidharrmadhātā ("Chang", then Luang Śrīvaravohāra), one of the four section chiefs in the Royal Pundits Department, who taught monks and novices at the monastery.

After his father had died in 1868 and his elder half brother Chulalongkorn had come to the throne, Vajirañana was back at the palace, receiving more education from his foster aunt, Princess Varaseṭhasutā.

King Chulalongkorn founded an English medium school on the palace grounds and hired the Englishman Francis George Patterson for providing Western education.

Dr. Gowan taught him English here and then and a little about medicine, and he had a big influence on Vajirañana's life conduct (stop smoking, drinking and some prodigal or even dissolute habits).

He learned some additional astrology (i.e. how to do calendars) from two other teachers, Khun Debyākaraṇa ("That") and "Pia" (Phrakrupalat Suvaḍhanasutaguṇa at Wat Rājapratiṣṭha).

King Chulalongkorn needed a reliable person such as Vajirañana in the Sangha, and he tried to persuade him to remain a monk even after his ordination according to custom.

Another senior monk, Phra Candragocaraguṇa (Candrarańsī), Abbot of Wat Makuṭakṣatriya, assisted in the ceremony as kammavācācariya.

After the ordination rite, Vajirañana spent the first Rains in Wat Pavaraniveśa, studying Pāli (e.g. with the Dhammapada commentary) and Buddhist scripture.

It consisted of secular subjects such as reading and writing Siamese, history, and some science beside religious studies and the preparation for the Pali exam, as the new academy also served the purpose of training monks to become teachers.

In 1898, King Chulalongkorn ordered Prince Damrong and Vajirañana to find a possible solution for providing the whole country with a primary education.

In 1906, King Chulalongkorn raised Vajirañana's princely rank to Krommaluang, although it was not royal custom to promote prince-monks until they reached advanced age.