Science at Jesus was notably represented by (Sir) Edward Bagnall Poulton (Jesus, 1873; Hope Professor of Zoology, 1893-1933), a Darwinian and exponent of the protective colouring of animals. From 1907, when the College laboratories opened under the direction of the new chemistry fellow D.L.Chapman, a strong scientific tradition grew up in the College, with a number of graduates becoming academic or professional research scientists. Celtic language studies flourished among graduate students, especially from the Welsh universities, during the Principalship (1895-1915) of the Celtic Professor, Sir John Rhys. Having studied philology at German universities, Rhys encouraged his students to follow his example, and brought many young Germans to Jesus College during the years before the First World War. Among his postgraduate students was John Lloyd-Jones (1885-1956), the first Professor of Welsh at University College, Dublin. A distinguished succession of Celticists (one Scot, John Fraser, and two Welshmen, Sir Idris Foster and David Ellis Evans) succeeded Sir John Rhys in the Chair between 1921 and 1996.

In 1907 the first two Rhodes Scholars entered the College. One of these, Professor Warren Ault of Boston University, a friend and contemporary of T.E. Lawrence, died in 1989 aged 102. Another member of that year was Pixley Seme, a leading Zulu chief and politician and a founder of the African National Congress. Early 20th-century West Indian students included the Barbadian educationist Grant Pilgrim (1884-1986) and the Jamaican Chief Minister Norman Manley (1893-1969).

Between the First and Second World Wars, Jesus College attracted large numbers of hard-working grammar-school boys, many of them from Scotland and the North of England. One of the most conspicuous of these in later life was the Labour Party leader Harold Wilson, Baron Wilson of Rievaulx (1916-95), Prime Minister 1964-70 and 1974-76. Other well-known 20th-century undergraduate and graduate members have included the quiz-master Magnus Magnusson; the poet Dom Moraes, who won the 1958 Hawthornden Prize as an undergraduate of 19; James Burke, science historian and one-time presenter of the Tomorrow's World and other BBC programmes; the historian Lord (Robert) Skidelsky; the novelist William Boyd (author of works including 'Brazzaville Beach', 'Armadillo' and the new James Bond novel 'Solo'); and Ffion Jenkins (a senior civil servant whose sister Manon, later a member of the Prince of Wales' staff, attended the College as a Sir John Rhys graduate scholar), wife of the former Conservative Party leader William Hague.