Supporting the stone seats on either side are two tombstones. Although very worn, one still shows a floriated cross, the other two rings and a shaft. There are three more such tombstones inside church, each bearing a floriated cross. One is on the north wall of the nave immediately opposite the porch and the others are in the south-west corner. They are probably late 131h century and were used to cover the remains of the early priors or vicars of Ecclesfield. The ornamental crosses indicate both the faith and the ecclesiastical rank of the deceased.
The arch on the wall of the porch dates from the thirteenth century and was found under the nave during re-pewing in 1823-5. It was probably over a doorway in the Early English nave.
Half hidden on the walls of many old churches can be found a strange figure — a face surrounded by leaves. He is known as the 'Green Man'. Ecclesfield has several green men in the roof bosses. Medieval masons could speak with their hands and it is astonishing how many human feelings — malice, humour, fear or tranquillity have been expressed by a few deft strokes of the chisel in this one figure.
There are several interesting and unique monuments and memorials in St Mary's. On the north wall of the chancel is a tablet to the memory of the Reverend Dr Alfred Gatty, Vicar of the parish 1839-1903. On the south wall are tablets to two former Vicars; the Revd Mansell, 1693-1704 and the Revd Steer, Canon of York, 1708-1745.
In the nave there are 3 interesting wall tablets. First is one made of alabaster and mosaic, in memory of Henry John Hawthorn, F.R.C.S. who died in 1903 after devoting 44 years of his life to the relief of sickness and suffering in the parish. On the north side is a small marble tablet placed by more than a 1,000 children to the memory of Margaret Gatty "as a token of gratitude for the many books she wrote for them". She was the wife of a former vicar of Ecclesfield, Dr Alfred Gatty. She wrote Parables of Nature and others. Below this tablet is one in marble and alabaster to the memory of Juliana Horatio Ewing, Margaret Gatty's second daughter who was well known for her books 'Jackanapes, The Story of a Short Life and other stories'. The Brownie movement took its name from one of her stories.
The font is octagonal in shape, as was the custom in Perpendicular churches. The eight sides stand for the seven days of creation and the beginning of the new creation in Jesus Christ. The eight panels are carved in strong relief. Four make up the year 1662, alternated with a heart, a Fleur-de-lys, a lozenge and a Tudor rose. During extensive alterations in 1823-5 the font was turned out into the churchyard to make way for an inferior substitute by the south transept door. It was put back in church in 1852. The font's position in the centre of church near the west doors indicated that it is through baptism we begin our Christian life. The font was relocated in 2020 to facilitate construction of a level access and is now in a side chapel off the south aisle thus forming a baptistry being used regularly for baptisms today.
The pulpit was given in 1876 in memory of William Frederick Dixon of Page Hall and his wife by their surviving daughters. The four panels depict scenes from the life of St Paul. These scenes were carved in Antwerp and the rest of the work was carried out locally. The pulpit continues to be used as the gospel is brought to the present generation. The lectern was also installed in 1876.
On the west wall and above the west door are several hatchments. These are framed heraldic bearings of deceased gentry. They contain the coats of arms of various local families, including the Shirecliffes and Foljambes - who have a memorial window, vault and several tablets in the church.
On the north wall are the colours of the Ecclesfield Volunteers. There are also six of their swords and 3 of the 4 original bugles. The Ecclesfield volunteers were 200 local men, who were "raised in 1803 towards the defence of the country during the war with Napoleon". These military relics were placed in the church on the restoration of peace. Two olive branches engraved on the plate enclose the regimental motto "Nothing is difficult to the brave and faithful".
In the south aisle is a Saxon Cross shaft and base stone.
This is probably the remains of a double memorial cross or preaching cross.