Instead of attending university, Hooker studied sculpture with Mahonri Young, William Zorach, and Edmond Amateis in New York, and later in Paris at Académie de la Grande Chaumière with Antoine Bourdelle.

Hooker was well travelled, studying wood carving in Germany, sculpture and dance in Greece, theatre design in Moscow, and painting in Leningrad, where she learned from the Russian avant-garde painter Pavel Filonov.

They amassed an extensive art collection, which included works by Jack Butler Yeats, Evie Hone, Mainie Jellett, Paul Henry, Nano Reid, John Piper, Henry Moore, Amedeo Modigliani, and Georges Rouault.

Hooker established the O'Malley collection of paintings by other artists in collaboration with the Irish American Cultural Institution.

Part of this collection is on permanent loan to the Irish Museum of Modern Art, and the other half with the Mayo County Council.

Hooker built a studio at Burrishoole in December 1943, but bought and moved into a house at 15 Whitebeam Avenue, Clonskeagh, Dublin in autumn 1944.

She held her first solo show in St Stephen's Green Gallery in 1950, which featured busts of Liam O'Flaherty and Denis Johnston.

She modeled numerous famous Irish figures, such as Mary Lavin, Eavan Boland, Austin Clarke, Dana Rosemary Scallon, and Éamon de Valera.

A 1973 retrospective of her work was held at Fairfield Court, Greenwich, Connecticut and was sponsored by the American Irish Historical Society.

The University of Limerick officially inaugurated the Helen Hooker O'Malley Roelefs Sculpture Trust in September 1993.