He came with his parents to Portage la Prairie in 1905. He later moved to Toronto in 1921. He acquired a reputation as a writer, painter, musician, and poet. Brooker was a charter member of the Canadian Group of Painters, and he won the Governor General's Award for fiction in 1936 for "Think of the Earth". He also wrote a controversial essay in 1931 titled "Nudes and Prudes". He was even known to himself pose nude for portraits, and once famously remarked to a hesitant young artist, "This is how I entered the world, and to deny my nudity is to deny the beauty of life itself."
Brooker argued in favour of nudes in painting because he felt that censoring art for the sake of children was tantamount to "lying to children", and thus for religious and spiritual reasons he felt censorship was a sin, and also because nudes are a valuable tool for educating children. He said:
"The tendency today is to tell children in a clean, straightforward, natural way about the functions of sex, so that they do not get their knowledge of it, half-guessed, from the filth they hear whispered in corners. And art is one method of acquainting children with the organs and functions of the body in an atmosphere of candour and beauty."