If Mawer's apprenticeship as a stone carver was served between the ages of fourteen and twenty-one years as per tradition, he would have been qualified to work as a top sculptor from about 1828.

It is not known where he served his apprenticeship, but since he was born in Nidderdale and married in Ripley, it is possible that he was apprenticed to a master stone carver at Ripon Cathedral where he could have gained the skills and knowledge that he used in all his works and taught to his apprentices.

As a "medieval sculptor" specimens of his work are to be seen in the numerous church screens, fonts and other forms of ecclesiastical decoration which he has executed in various parts of the kingdom.

[28][29] Media related to Leeds Parish Church at Wikimedia Commons This is a Grade II listed building in Queensbury, Bradford.

Media related to Holy Trinity Church, Queensbury, West Yorkshire at Wikimedia Commons This is a Grade II listed building.

[37] When Mawer carved the label stops and corbels of the building in the form of heads, he and William Ingle were already "Mallinson and Healey's favourite stone masons".

"[18][41] Media related to Saint Paul Church (Manningham, Bradford) at Wikimedia Commons Mill Hill Chapel is a Grade II* listed building in Leeds City Square, opened on 27 December 1848,[42] and designed by architects Bowman & Crowther of Manchester.

[49][50] The Bradford Observer said in 1849:[48] "The font (very similar to the one in S. Mary Magdalene, Oxford), which is placed near to the West end of the Nave, is in keeping with the architecture of the church, which is flowing decorated, and is extremely beautiful both as to design and execution.

It is of Caen stone, and together with all the carved work of the church, from the chisel of Mr Mawer of Leeds, of whose skill in this branch of ecclesiastical decoration it were needless to speak whilst such specimens of this, and many others scattered up and down the country, remain to testify.

At the consecration the Leeds Intelligencer reported:[51] Over the inner doorway of the porch as we enter, the following text is carved on the face of the arch in the old church letter: "They that wait upon the Lord shall renew their strength."

[51] Media related to St Matthew, Bankfoot, Bradford at Wikimedia Commons This building, designed by James Mallinson and Thomas Healey, is not listed.

[66] Media related to Former Church of St Mary, Quarry Hill, Leeds at Wikimedia Commons This building is Grade II listed.

[68] "The chancel arch has moulded piers and capitals, having carved on them, on the north side, emblems of the Passion, and on the south, Angels carrying musical instruments ...

"[69][70]The English Heritage listing description includes the following: "[Exterior:] Openwork parapet and tall crocketted pinnacles on corbel brackets of figure heads and beasts.

[71] Media related to St Mary the Virgin, Gomersal at Wikimedia Commons This is a Grade II* listed building,[72] on Main Street, Barmby Moor, East Yorkshire.

Most of the local inhabitants turned out for the foundation ceremony, which included in its procession all those contracted to work on the building, "(forty in number) carrying banners with appropriate mottoes."

Ascribed to Mawer and Ingle of Leeds, who were frequently patronised by Healey, they offered no scope for the firm to enhance their reputation, but if the poor little font is theirs also, as stated by the notes in the church, then surely one of their apprentices must have been delegated the work.

"[78] However, at the consecration the Yorkshire Gazette said: "The handsome new font of Caen stone does credit to Mr Mawer of Leeds, by whom the corbels and interior carving were executed.

The cornice of the reredos is ornamented with carved ears of corn, grapes, leaves &c. This exquisite piece of work has been most creditably and satisfactorily executed by Messrs. Mawer & Ingle, carvers, from designs of Messrs. T.H.

[83] The 1861 west window made by Hughes of London and dedicated to Canon Robert Deaville Owen (1823−1904), features the Apostles James, Paul and Peter.

[84][85][86] Media related to St. James' Church, Boroughbridge at Wikimedia Commons This is a Grade II* listed building, designed by Henry Francis Lockwood and William Mawson.

[88] The hall cost about £25,000, and opened with a three-day music festival, which overwhelmed the town's accommodation and transport with large numbers of nobility and other visitors.

It is of an octagonal shape, of the perpendicular style of architecture, so as to correspond with the church, designed by Cuthbert Brodrick, Esq., the architect of the New Town Hall, and executed by Mr Mawer of Oxford Place.

Around the top is the name of the donor, in Old English characters upon a wreath of leaves, as follows: This font is humbly offered to the glory of God, by Charles Gascoyne Maclea - 1853 (Leeds Intelligencer 5 November 1853)[107][108]St Marks was used as a location in the TV series The Beiderbecke Affair.

[112] Media related to St John Wortley, archive images at Wikimedia Commons This is a Grade II* listed building, designed by Perkin and Backhouse of Leeds.

Its plan is octagonal, and each side has a well-relieved and moulded arched canopy, with sunk emblazoned panel, on which are written the following appropriate text: "One Lord," "One Faith," "One Baptism," "One God and Father of all."

(d.1865) Although the parish district was constituted in 1851, local contributors and bazaars took time to raise funds, so that the foundation stone was not laid until 20 October 1853.

[123][124] Media related to Former St Stephen's Church, Burmantofts at Wikimedia Commons This is a Grade II listed building at 48 Altion Street, Leeds, West Yorkshire, occupied by Starbucks since 2016.

The carved stone decoration on the exterior of the building, so universally admired, was almost the last work of the late Mr. Robert Mawer, a man whose taste and judgement (for much of it was his own design) were such that his place in Leeds cannot readily be supplied."

In August of that year, the Bradford Observer reported: "There has been added a reredos of Caen stone which is most beautifully carved, being the workmanship of Mr. Mawer of Leeds.