Knox returned to Australia in 1886 and joined his brother George in practising law. When George died in 1888, Adrian took over the practice, and soon became one of the most successful lawyers at the Sydney bar. Between 1888 and 1890, he reported
equity cases for the New South Wales Law Reports. After being reelected at the
1895 election, he retired from the parliament in 1898, to concentrate on his legal career. At this time, he was also a director of the
Australian Mutual Provident Society and a founding member of the
Walter and Eliza Hall Trust. Knox was made a
King's Counsel in 1906, and shortly after was offered a position on the bench of the
Supreme Court of New South Wales, which he declined. Also in 1906, Knox became Chairman of the
Australian Jockey Club, indulging his passion for
horse-racing. In 1910, Knox's horse "Vavasor" won the
Sydney Cup. He remained chairman until 1919. During
World War I, Knox left his practice and traveled to
Egypt, where he served as a Commissioner for the
Red Cross. He served on the NSW Bar Council from its foundation in 1902 until 1910, and again from 1916 to 1919. ==Judicial career==