He attended University of British Columbia (University of British Columbia) and University of Toronto, receiving a Doctor of Philosophy from the latter in 1936.
He helped build the University of British Columbia"s creative writing department and fostered the careers of several major Canadian writers. Thereafter, he worked at the University of Manitoba, heading its English department until 1946 when he took a position at his alma mater University of British Columbia. When Garnet Sedgewick retired in 1948, Daniells became department head, holding that post until 1965. During that time, he helped establish a Creative Writing Department at University of British Columbia and also promoted the university"s funding of studies in Canadian Literature.
In 1965, Daniells was named the first University Professor of English Language and Literature.
Daniells helped the writing careers of Margaret Avison, Earle Birney, Joy Coghill, Daryl Duke, Roderick Haig-Brown, Eli Mandel, Margaret Laurence, Eric Nicol, Sheila Watson, Phyllis Webb, Adele Wiseman, and George Woodcock, among others He retired in 1974. There is a biography of Daniells by author Sandra Djwa. first University Professor of English Language and Literature (1965).