He was the youngest son of John Knight of Fairlinch, Devon, by Margaret, daughter and heiress of William Bruce of Llanblethian, Glamorgan.

He left Sherborne in 1805, and, after spending two years with a mathematical tutor, was articled to a solicitor in Lincoln's Inn Fields.

The increase of his chancery practice soon caused him to abandon the common law bar, and he confined himself to practising in the equity courts.

In Michaelmas term 1829 he was appointed a king's counsel, and on 6 November in the same year was elected a bencher of Lincoln's Inn.

[1] In politics Knight was a Tory, and in April 1831 he was returned for Bishop's Castle, a pocket borough belonging to Edward Clive, 1st Earl of Powis.

In Michaelmas term 1842 he undertook the further duties of chief judge in bankruptcy, and seven years later the exercise of the jurisdiction of the old Court of Review was given to him.

[1] Knight-Bruce wished to shorten procedure and save time in the discussion of technicalities, and in some of his decisions, which were over-ruled by Lord Cottenham, he anticipated reforms which were subsequently made.