The S porch (disused) has stone benches and a single collar-beam truss on brackets. In the W wall is a wall tablet. The pointed S door has a C14 studded door. In the N porch are stone benches and a re-set medieval cross slab in the E wall. The pointed N doorway has C20 boarded doors.
The interior is plastered and windows, including clerestorey, have freestone rere arches. The nave has 3-bay early C14 arcades of octagonal piers on square bases, with simple capitals, pointed arches with 2 orders of hollow chamfer, and hood moulds with large head stops. On the S side the broad respond between nave arcade and later transept arch has a cusped niche. The nave has a 7-bay corbelled arched-brace roof with windbraces, and subsidiary trusses behind the purlins. Aisles have trusses on corbelled brackets and windbraces. In both aisles a corbelled shelf is beside the entrance, which on the S side has a shallow round-headed niche. The S aisle also has 2 arched tomb recesses and a cusped piscina, all C14. The tower arch has 2 orders of continuous chamfer, and boarded doors with false strap hinges. In the lower stage of the tower is a heavy framed ceiling on corbels. The S transept has pointed arches from nave and aisle, with 2 orders of sunk roll mould, a plainer outer order and hood mould. In the S transept is a cusped piscina in the S wall, and inserted cupboard below it. The upper section of a winding rood stair survives above the arches at the junction of transept and chancel.
There is no structural division between nave and chancel, except a lower cusped arched brace with struts above. The chancel has a lower eaves line, an arched-brace roof of 2 wide bays, similar to the nave but without windbraces. On the N side is an arch to the organ recess and vestry. It has 2 orders of sunk roll moulding, and hood mould with head stops. In the chancel is a floor of re-set grave slabs and C19 decorative geometrical-pattern tiles. The sanctuary has richer tile work. The wooden reredos has 5 blind panels behind the altar, of which the central 3 are higher, with delicate 2-light blind tracery, and similar but lower panels R and L, all under a vine cornice with brattishing. In the S wall, salvaged medieval floor tiles have been assembled to form a large wall panel.
The major interior fixture is the imposing 5-bay rood screen, erected in the period 1488-1504 and well restored in the C19. It features the badge of Sir Richard Pole (eagle's claw grabbing a fish), who was constable of Conwy Castle 1488-1504. Each outer bay has a panelled dado under quatrefoil friezes, and 4 lights with delicate tracery. The central bay has double wooden gates, with an upper tier of linenfold panelling. Main uprights have thin shafts with capitals, below deep ribbed coving and pendants. On the chancel side the coving is given additional support by 2 later posts. The cornice has 2 orders of foliage trails, incorporating various motifs including the badge of Sir Richard Pole. The choir stalls are contemporary with the screen. They are L-plan on both N and S sides, backing on the rood screen, with blind-traceried ends and poppy heads. Original fronts also have blind tracery, but another bench has been added on each side, also with traceried ends, and with later turned balusters to the front.
The C20 communion rail is in wood. In the N aisle is a C20 war memorial chapel with screen a simplified Tudor-Gothic style and a panelled wainscot inside incorporating a roll call. At the W end of the nave is a Tudor-Gothic hymn-book stall of the C20, with panel dado and blind arches, then open ogee arches with delicate tracery, foliage cornice and brattishing.
The Perpendicular font is on a stepped plinth. The plinth was probably re-used from elsewhere, although it is illustrated in its present position in 1835. The font is badly weathered but its intricate carving can still be appreciated. It has a lead-lined octagonal bowl with quatrefoils and rosettes. An octagonal pedestal is surrounded by an detached arcade of cusped arches, and buttresses. The pews are C19, with shaped ends. The C20 late-medieval polygonal wooden pulpit has open cusped tracery.
Memorials: There are numerous monuments, both freestanding tombs and wall tablets. The most important is in the SE corner of the chancel, a tomb chest with arched hood to Robert Wynn (d 1598) and Robert Wynn (d 1664). Aligned E-W, its W face has relief heraldry and inscriptions on both hood and chest. Other chancel monuments are wall tablets and plaques. Above the Wynn tomb in the E wall is a tablet with relief inscriptions and arms to John Wynn (d 1637), surmounted by pinnacles and achievement. Next to it is a plain brass to Rev Morgan Morgan (d 1870). On the N side of the altar is a marble tablet to Margaret Coytmor (d 1684), an inscription panel with pilasters, on a winged cherub, surmounted by a flaming urn. Next to it are simpler relief tablets to Anne Apthorp (d 1786) and Katherine Robeson (d 1621). In the N wall a memorial to Mary Owen (d 1837) is a marble tablet with urn against a black background, by E. Gaffin of London. A plain painted tablet in a wooden border is to Jane Fletcher (d 1708). The S chancel wall has grave slabs re-set against the wall with dates 1601, 1586 and 1666, although not all are visible. A classical tablet to Cadwaleder Wynn (d 1719), erected by Watkin Wynn in 1752, has a panel on an apron with cherub, pilasters and entablature. To its L is a simple tablet to Richard Williams (d 1765, aged 11).
In the nave N wall, opposite the S transept, a tablet to George Coytmor and wife (d 1738, 1758) is by B. Bromfield. It is of marble with inlay star patterns, Vitruvian-scroll moulding to the entablature, and pediment incorporating a relief roundel with achievement. A tablet, with pilasters and corbels, partly draped, commemorates Hephzibah Williams (d 1832). A marble tablet to Henry Pringle has flanking inverted torches and an achievement, on a black background.
In the transept E wall is a tablet to Robert Howard and wife (d 1776, 1780), by B. Bromfield and similar to the Coytmor tablet in the nave. Of marble, with inlay star patterns, it has a corbelled apron to a sarcophagus with inscription, and tall pediment with a fluted urn. Next to it is a weathered freestone Renaissance tablet with Latin inscription to Johannes Hooke (d 1600) below kneeling figures in high relief, guilloche-moulded border, and surmounted by pinnacles and achievement. In the S wall is a simple slate tablet to William Holland (d 1703). In the W wall are simple slate tablets to Edward Holland (d 1734) and Jane Williams (d 1694), and freestone tablet to Margaret Roberts. Against the S wall are 2 chest tombs. Below the piscina is a tomb with slate slab to Robert Williams (d 1760). On the W side is a tomb with cracked freestone slab, coats of arms and 2 inscriptions, to Sir Edward Holland (d 1584), and William Williams and wife (d 1641, 1677).
In the S aisle are 2 tomb recesses. The easternmost has a female effigy in low-relief slate. The westernmost has a re-set medieval grave slab. A memorial to the sculptor John Gibson (1790-1866) is by W. Theed of London. It comprises a marble bust in a cusped recess, with hood and foliage stops, below which is a marble inscription panel. There are also wall tablets to Cornelius Foulkes (d 1754) and Thomas Williams (d 1784).
Against the N aisle N wall is a table tomb with slate slab to John Williams (d 1706), on later shaped legs (in 1835 this slab was in the NE corner of the chancel). The E wall has 2 marble tablets with black pedimented backgrounds, to Silence Holland (d 1812) by T. Franceys of Liverpool, and Diana and Owen Holland (d 1795). In the N wall is another similar Franceys memorial, to Rev Hugh Williams and wife (d 1809, 1843). A slate tablet erected by the Burma Star Association commemorates lives lost in the Far East. Marble tablets are to Sir David Erskine (d 1841) and Jane Erskine (d 1826, aged 3). A brass plaque commemorates Elizabeth Roberts. Old grave slabs are set into the N aisle floor.
Stained glass: The E window, probably dating from Scott's 1872 restoration, depicts the Ascension and Evangelists. The N window, depicting the Last Supper, is by Mayer & Co of London and Munich, post 1882. In the S transept, one E window shows the angel of the Resurrection, post 1870, the other patterned coloured glass dated 1879. The S window has similar patterned glass. The W window shows the Welsh Bible translators William Morgan and William Salebury, post 1936. In the S aisle, the pair of lancets toward the E end show Saints Mary and Margaret, post 1915. In the W window the pair of lancets depict the single scene of Christ healing the sick, by A.L. Moore of London, post 1912. The E window of the N aisle shows re-set glass showing Christ blessing a child, carrying the cross and with Mary Magdalene, by H Worwick, dated 1854. The N window in the nave shows Christ preaching, post 1888.