John (Johannes) Rosewell was ordained as a Deacon at Christ Church Cathedral, Oxford on 31 March 1661.
While at Corpus Christi, in the period 1653–54, Rosewell was prescribed for "a very hot stomach" by the apothecary, Jeremiah Webbe.
Rosewell succeeded Thomas Mountague as Head Master of Eton in 1671 and was the last "alien" (non-Etonian) to be elected to the position for many years.
Rosewell seems to have greatly increased the reputation of the school, and is styled by one of his pupils, ludimagister celeberrimus (renowned schoolmaster).
According to a rumour of the day, his resignation was caused by his falling into a fit of melancholy madness, in consequence of having killed a boy by immoderate flogging, and fancying that the King's messengers were coming to arrest him.