Cafodd yr eglwys Sant Ioan ei chysegru ar 6 Gorffennaf, 1837. Ar y pryd, roedd yn eglwys dosbarth ym mhlwyf Rhiwabon.
Crëwyd y plwyf newydd Rhosymedre ar Mai 24, 1844, oddi wrth y trefgordd Coed Cristionydd a rhan o'r trefgordd Cristionydd Cynrig, a oedd, tan hynny, wedi bod ym mhlwyf Rhiwabon. Ar 28 Hydref 1879, aeth rhan o blwyf Rhosymedre i'r plwyf newydd Penycae.
St. John's church was consecrated on 6 July, 1837. At that time, it was a district church within the parish of Ruabon.
The new parish of Rhosymedre was created on 24 May 1844, from the township of Coed Cristionydd and part of the township of Cristionydd Cynrig, which, until then, had been in the parish of Ruabon. On 28 October 1879, part of the parish of Rhosymedre was transferred to the new parish of Penycae.