In 1930 she married Frank Hogg, a fellow student and astronomer. They had three children, Sally, David and James. In 1946, Frank became director of the David Dunlap Observatory, a post he held until his sudden death in 1951. In 1985, she married F.E.L. Priestley, Professor Emeritus of English at the University of Toronto, who died 1988.

Helen Sawyer Hogg's work focussed on globular clusters, in particular the variable stars within them. She published more than 200 papers, the Catalogues of Variable Stars in Globular Clusters, and a number of historical articles, mostly in the Journal of the Royal Astronomical Society of Canada, JRASC, and was active member in a number of professional societies.

Professor Helen B. Sawyer Hogg Priestley passed away on January 28, 1993 in Richmond Hill, Ontario.

Already during her lifetime, she had been honored by the astronomical community by naming asteroid (2917) Sawyer Hogg in 1984; it had been discovered on September 2, 1980 by E. Bowell at Anderson Mesa and provisionally designated 1980 RR. On May 20, 2004, she was included into the Canadian Science and Technology Hall of Fame in Ottawa.

When researching globular cluster publications, Helen recovered a longly forgotten letter by Pierre Méchain (Sawyer Hogg 1947, Sawyer 1948), in Bode's Jahrbuch for 1786, in which he disclaims his discovery of M102 and lists four newly discovered deepsky objects which she proposed to be added to the Messier catalog: NGC 4594 as M104 (already added by Camille Flammarion in 1921), NGC 3379 as M105, NGC 4258 as M106, and NGC 6171 as M107.