Tower has C19 panelled boarded ceiling, encaustic tiles, narrow pointed N door to stair and plain tall pointed tower arch. Body of church has plastered whitewashed walls and later C19 tile floors. Plastered 5-bay arcade of plain pointed chamfered arches on octagonal piers with caps and raised 'sleeves' to bases. 1861 nave and aisle roofs of 13 and 19 close-set broad low trusses on hammer-beams braced from timber corbels below, the braces ornamented with shields or rosettes. Cornice with rosettes between trusses, heavy tracery in low space above tie-beams. Nave N wall has 4 pointed tomb recesses. N transept has arch replaced by 1851 timber Tudor-arch on angel corbels, and 4-bay C17 roof of thin collar trusses with false hammerbeams, pendants, and carved thin raking struts to high collars with pendants. Ovolo-moulded double purlins, boarded panels. Large pointed recess on transept W wall.
Chancel has pointed arch to nave and segmental-pointed S arch with responds as on nave arcade. Shallow-curved panelled chancel ceiling of 1865. Pointed vestry door with iron hinges of 1866. Two steps to sanctuary, encaustic tile paving.
Two vestries: W room of 1886 with panelled boarded ceiling, 1886 door between with open cusped top panels and fine inset ironwork below. E room of 1865 has flat-boarded ceiling also.
S porch, refitted 1969 as war memorial to Grammar School pupils, has plastered medieval barrel vault and fine heavily moulded C14 S doorway with hollow between 2 keel mouldings, the arch stones roughly alternately red and cream. S aisle E has tile pavement by Maw & Co 1876 with border of mitres in front of consistory court pews. Cambered-headed S door.
FITTINGS: Octagonal stone late medieval font, retooled 1857, with quatrefoil and rosette panels, chamfered below with vigorous leaf carving, on octagonal shaft with cusped pointed panels. Ornate pulpit of 1892 by Jones & Willis, black marble plinth, ashlar base with 8 pink marble shafts, and bands of marble in cornice, under oak diagonally-set square pulpit with traceried panels, one with carved relief, and carved saints under canopies at angles. Ashlar steps with brass rail. Brass angel lectern of 1888 by Jones & Willis. Organ between chancel and S aisle, 1790s by G. Pike England in case with centre rounded tower and square outer stacks, minimal Gothic detail. Nave W gallery possibly of 1789, altered, 6 plain iron posts, flat underside, and pitch-pine front of 1855 with diagonal grid. Pews of 1855 by James Wilson with poppyhead finials and doors. Panelled low screen across chancel arch, the panelling carried around to pulpit stairs. Chancel stalls of 1892 by Jones & Willis with cusped panels to fronts, corner shafts, quatrefoil panels to bench ends and panel doors. Timber rails of 1866, Gothic open panels with wrought iron inserts. Oak Gothic reredos of 1892 by Jones & Willis, centre tabernacle, 2 bays each side with finials, and outer bays with statuettes under canopies. Side panelling 1927. Consistory court fittings of 1866 including enclosed pew with centre table, Gothic canopied bishop's stall in row behind, with mitre in roundel and 4 ornate pews the other side. S aisle timber screen probably c.1865. Under W gallery is fine oak 1709 'faculty pew', with plinth, fielded panels, turned columns and ornate moulded cornice. Painted grained within, benches on 4 sides and corner entries. C18 family pew of Griffith Lloyd by S pier of chancel arch not in situ 2002. Mayor's seat opposite: heavily carved chair, 1851 by Isaac Davies, and arched wrought iron frontal with borough arms and fasces. Nearby deal altar table dated 1716. Former marble altar by D. Mainwaring 1829. In W vestry late C18 painted Commandment boards in pilastered frame. Two faded early C18 benefaction boards in E vestry and clock dated 1803. Fragment of C17 wall-painting on E wall of SE chapel. Reset C15 stone shield with Henry V arms by SE chapel door, found 1878 near Priory site.
MONUMENTS:Carmarthen church has the most extensive collection of church monuments in SW Wales, some of the highest quality.
In S aisle Sir Rhys ap Thomas effigy on C16 tomb chest, restored in 1866, originally brightly coloured. Effigy of Sir Rhys is complete, in armour with dog at feet and helm under head, effigy of his wife is not apparently made for the same tomb as too small. Tomb chest has canopies over carved figures: S side has 4 figures each with double canopy, 2 original, and 3 pilasters with carved arms and small figures. E end has a blind traceried rose with coat of arms. N side is mostly C19, one original figure. Nave N second niche has C14 coffin lid with carved head and side inscription possibly to a Richard Rosb(u)r. Also a carved stone boss, possibly C13. In 4th niche, the top half of a medieval male effigy with hand on chest. In tower base a Roman pillar altar.
WALL MEMORIALS:: Nave N: Thomas Morris (d 1839) neo-Grec, by Tyley; small sarcophagus plaque to Herbert P. Ball (d 1798), by Wood; plaque with urn to Mary Oakley (d 1801) by Foster & Co. Very fine pair of joined large monuments with cherubs under, scrolled sides, and 2 cherubs over left plaque holding portrait ovals to John Phillips (d 1730) and arms over right plaque to Ann Philipps (d 1720). Arch between over plaque with portrait oval to Rechell Lloyd (d 1723). Nave E fine Baroque monument with fluted pilasters, cherubs and curved pediment to Sir George Lewis (d 1715). N transept: W wall large slate plaque to Ann Philipps (d 1720) and family to 1734; in recess coloured marble pilastered memorial to Elizabeth Evans (d 1765); slate plaque in big ashlar frame to David Lloyd (d 1752) . N wall neo-classical plaque with small urn to Thomas Cookes (d 1802), by J. Bacon Jr; oval plaque with urn to Eliza Miers (d 1772). E wall massive black sarcophagus to Sir James Hamlyn Williams (d 1829) by D. Mainwaring; oval plaque like Miers memorial to Jane Philipps (d 1766). Chancel N oval plaque to Thomas Jones of Job's Well and descendants to 1810, by D. Mainwaring; marble plaque with urn and weeping willow to J. Jones of Ystrad (d 1842) designed by the painter T. Brigstocke made by Gaffin of London 1856; Rev R. Prichard (c1715) portrait bust in recess between carved pilasters, cornice, plaque with cherubs and arms below. Over vestry door Mary Howell (d 1721-2) portrait bust over scrolled plaque.
In NE vestry unusual painted wood Baroque surround with scroll pediment to Anna Wotton (d 1719); plaque with urn to Rev John Thomas (d 1793) by F. Lancashire & Son of Bath.
Chancel N Richard Vaughan (d 1724) by William Palmer, fine quality, with curved head over cherub-head relief; William Lloyd (d 1710), grey marble panelled pilasters, cornice and arms on pedestal; Rev. Edward Meyrick (d 1713) with cherub heads, scrolled sides and arms over cornice; John Lloyd (d 1802) and wife (d 1814) by Drewett & Co, draped urn; Edward Davids (d 1758), pedimented. On chancel E wall, James Hughes, (d 1803), mourning female and urn, by Wood, Esther Williams (d 1802) oval with urn, by Drewett & Co; Baroque oval plaque with twisted columns and missing pediment, to Mary Harries (d 1700). Chancel S: Lady Anne Vaughan (d 1672) fine painted kneeling figure in recess between Corinthian columns; double large plaque with urn to infant children of H. Lawrence (dd 1834-8) and to James Hughes and family to 1841, by J. Mainwaring. Small lozenge to Mary Mansel (d 1811) by Cooke. Big oval plaque with urn and scrolls, to J. Williams (d 1687). Plaque to Lady M. Mansel (d 1811) by Cooke. Right of organ, small plaque with flaming urn to T. Holliday (d 1787) by R. Isbell. In chancel floor, floor slab by D. Mainwaring to Charlotte Dalton (d 1832) and Margretta Dalton (d 1839).
S aisle: N wall: Rowland Phillips (d 1726) segmental pediment and fluted pilasters; fine double monument to John William of Bwlchgwynt (d 1739) and wife (d 1744) with fluted pilasters and double curved pediments. E wall: G.W. Bevan (d 1768) coloured marble by R. Morgan; Frances Diggle (d 1797) oval with urn by W. Paty; John Lewes (d 1742), open pediment and cherub; Mary Osborne (d 1730), with finely carved skulls below and curved pediment. S wall: Jonathan Oakley (d 1677), baroque with twisted columns and half-length figure; Sir John Scurlock (d 1682) baroque with twisted columns, skulls and broken curved pediment with fruit; Sir William Nott (d 1845) large marble plaque with sword above, by J. Loft; M. Roch and D. Davies, (both d 1818) each with sarcophagus, probably by Mainwaring; Sir Richard Steele (1671-1729), brass memorial erected 1876; Bishop Robert Ferrar (burnt 1555) memorial 1843 by J. E. Thomas, with mitre and bible; Catherine Morgan (d 1767) open pediment and columns; John Thomas (d 1731) crude ashlar with curved top; Dr John Morgan (d 1784) by T. Paty fine Grecian woman and urn; Rev. W.H. Barker (d 1816) by D. Mainwaring, sarcophagus over shield plaque; B. Waugh (d 1827) and wife (d 1840); Fanny Shirley (d 1764); Sarah Shirley (d 1783) pedimented; Richard Philipps, organist, (d 1823); Susanna Richards (d 1742) with fluted pilasters and three colours; Maria Warlow (d 1809) with urn over shaped plaque by Mainwaring; James Hills d1818, with urn, by Mainwaring.
Stained glass: Nave N 2 Courage & Victory, to Lt P. Girardet (d 1914) Kempe-style; N3 1903 Christ & St Peter, possibly by Powell; N4 to M. Thomas, finely drawn High Victorian Gothic, Crucifixion and Resurrection, 1870 by Heaton, Butler & Bayne. N transept N big colourful window with much pattern work and 3 scenes, Call to Peter, Feed my Sheep, and Christ stilling the waves, by Wailes of Newcastle, 1866, to David Morris MP (d 1864). Chancel N1 1978 by John Petts 'the desert shall bloom'. E large 5-light window of 1873 by Alexander Gibbs, to Isaac Horton (d 1872) 5 scenes from the Crucifixion and 4 top-light panels including Light of the World and Feed my sheep. S aisle has 3 major works of 1864 by Joseph Bell of Bristol: the E 5-light of Christ, St Peter and Evangelists, neo-classical drawing style but Gothic tabernacles, S wall 4 th, 3-light, Faith, Hope & Charity, to Miss A. Lewis, and S wall 3rd, 6 vesica-shaped panels of Works of Mercy, to Charles Morgan. S aisle 2nd, 1926, 3 warrior saints to R. Lester, probably by Shrigley & Hunt of Lancaster. S aisle 1st, 1987 by John Petts, tree of love. S aisle W has panel of armorial glass, earlier C19. In NE vestry a panel of Lamb of God.