He was educated at Attercliffe Academy under Timothy Jollie, and afterwards studied for a year under Matthew Henry at Chester.
In 1717 Mottershead became minister of Cross Street Chapel, Manchester, and held this post till his death.
When the Young Pretender entered Manchester in November 1745, Mottershead was selected as hostage for a monetary fine; but he had a warning in good time and made his escape.
During his long ministry at Manchester, Mottershead, whom Robert Halley calls ‘a very quiet peaceable man,’ passed from Calvinism to a type of Arianism.
He married, first, at Kingsley, the eldest daughter of Bennett of Hapsford, Cheshire; she died in October 1718, leaving four children: He married, secondly, in January 1721, Margaret (d. 31 Jan. 1740), widow of Nathaniel Glaskell of Manchester; he was her third husband.