In 1838, he was appointed to a tutorship at Upper Canada College and was ordained a priest of the Church of England.

On August 14, 1841, he married Harriet Eugenia Baldwin (d. 1843) and they had one daughter, Henrietta Millicent Scadding (June 1, 1842 – 1926).

In 1847, Scadding became the rector of the Church of the Holy Trinity in Toronto, a post he held until 1875.

Scadding wrote many books, including the Memorial of the Reverend William Honywood Riply (1849), Shakespeare the Seer—the Interpreter (1864), Truth's Resurrection (1865), Christian Pantheism (1865), Toronto of Old (1873),[2] The Four Decades of York, Upper Canada (1884) and A History of the Old French Fort at Toronto (1887).

Scadding was a co-founder and the first president of the York Pioneers, a Toronto-based historical society that preserved Scadding Cabin, which had been built by his father in the early days of the town of York.