On the reconstitution of the Court of Appeal in 1876, Brett was elevated to the rank of a Lord Justice of Appeal. He was sworn of the Privy Council at the same time. After holding the position for seven years, he succeeded Sir George Jessel as Master of the Rolls in 1883. In 1885 he was raised to the peerage as Baron Esher, "of Esher in the County of Surrey". He opposed the bill proposing that an accused person or his wife might give evidence in their own case and supported the bill that empowered Lords of Appeal to sit and vote after their retirement. The Solicitors Act 1888, which increased the powers of the Incorporated Law Society, owed much to his influence. In 1880, he delivered a speech in the House of Lords, deprecating the delay and expense of trials, which he regarded as having been increased by the Judicature Act 1873. He retired from the bench at the close of 1897, and was created Viscount Esher, "of Esher in the County of Surrey", a dignity never given to any judge, Lord Chancellors excepted, for mere legal conduct since the time of Lord Coke.