His father, John Brook, was also a lawyer and serjeant-at-law; he died in 1525, and was buried in the church of St. Mary Redcliffe, Bristol, having been principal seneschal of the neighbouring monastery.
On 3 February 1547, the first week of Edward VI's reign, he received the coif, the degree of serjeant-at-law having been bestowed on him as one of the last acts of Henry VIII.
On 25 November 1551 he was appointed king's serjeant, and when, two years later (1 September 1553), Sir Henry Bradshaw was removed, he succeeded him as lord chief baron of the exchequer.
On 2 October, the day after Queen Mary's coronation, Brook and others, according to Henry Machyn, were dubbed knights of the carpet.
He was twice married: first to Katherine, daughter of Giles Brugge, 6th Baron Chandos, who was the widow of Leonard Poole (d.1538); secondly, to Margaret, daughter of Richard Butler of London, who had already survived two husbands, Andrew Fraunces and Alderman Robert Chertsey, and, surviving Broke, married Edward North, 1st Baron North, and was buried in the chancel of the church of St. Lawrence Jewry, London.