Browne Willis gives the dedication as either Marcello (1733) or Marcellus (1754), although an earlier dedication to Deiniol appears likely. The church was originally a chapel of Bangor Is-coed, before Marchwiel became a parish in its own right. A board at the church, of uncertain date, states that the church was dedicated to Marcella in 1537. D.R. Thomas notes the name of an adjoining tenement as Tyddyn Daniel, which was purchased in 1626, and recorded in the church terrier in 1749. Rice Rees gives Deiniol as the original dedication.

The association with Marcella seems to be derived from the place-name, which can be traced back to the thirteenth century.