The son of Edward Ewer, born at Belchamp St Paul, Essex.
On 1 March 1738 he was appointed by patent to a canonry of Windsor, with which he subsequently held the rectory of West Ilsley, Berkshire.
In 1749 he became rector of Dengie, Essex, and on 4 November 1751 was instituted prebendary of Moreton cum Whaddon in Hereford Cathedral.
Ewer took occasion, in a sermon preached before the Society for the Propagation of the Gospel in Foreign Parts, 20 February 1767, to reproach the American colonists because they failed to see any use for bishops or episcopally ordained ministers.
He then proceeded to brand them as "infidels and barbarians" living in "dissolute wickedness, and the most brutal profligacy of manners".