Walter Manifold was the son of Thomas Manifold, a pioneer grazier in the western district of Victoria who had represented Warrnambool in the Legislative Assembly in 1861. He was educated partly in Melbourne and partly in France and Germany and qualified as a solicitor, although he never practised. Instead he became a grazier, owning first Sesbania station in northern Queensland from 1876 to 1884 and then Wollaston station near Warrnambool which was later sold for soldier settlement. In 1885 he married Fanny Maria Smith.

He was elected to the Legislative Council for Western Province in 1901, and held the seat until 1924, as a non-Labor, later Nationalist member. From 1910 until 1919 he was the unofficial leader of the Legislative Council, and in 1919 was elected President. He was knighted in 1920. He retired as President in 1923 due to ill health and in early 1924 resigned his seat. He died four years later at Toorak.