In 1891, Reginald graduated from Victoria University, where he obtained Bachelor of Arts degree. Reginald continued his studies and the following year, he got Bachelor of Science degree at the same educational institution.
In 1893, Daly received Master of Arts degree, graduating from Harvard University and in 1896 he became a Doctor of Philosophy.
In 1892, Daly served as a mathematics instructor at Victoria University. Some time later, in 1898, Reginald was appointed an instructor of physical geography at Harvard University in Cambridge, a post he held until 1901, when he started to work as a geologist for the Canadian International Boundary Commission. Daly conducted surveys of the mountainous region of western Alberta and southern British Columbia for six years.
During the period from 1907 to 1912, Reginald worked as a professor of physical geology at Massachusetts Institute of Technology.
Since 1912 to 1942, Reginald held the post of a professor of Geology at Harvard University.
In 1946, Daly proposed the impact theory of lunar creation, which countered two prevailing notions: George Darwin's hypothesis, that the Moon spun out of the primordial Earth due to centrifugal force and another fashionable theory, that the Moon was a captured wayward asteroid. Daly applied Newtonian physics to make his point, which was later validated.
Reginald Daly also developed the concept of magmatic stoping and his work in the Pacific islands stimulated ideas about glacial control over the creation of coral reefs.
During his lifetime, Daly worked as a lecturer at different colleges and universities, including Yale University, Northwestern University, Harvard University, University of Virginia and the Lowell Institute in Boston, Massachusetts. He also served as an associate editor of the American Journal of Science.
"At bottom each "exact" science is, and must be speculative, and its chief tool of research, too rarely used with both courage and judgement, is the regulated imagination."
"Earthquakes traveling through the interior of the globe are like so many messengers sent out to explore a new land. The messages are constantly coming and seismologists are fast learning to read them."
"Our earth is very old, an old warrior that has lived through many battles. Nevertheless, the face of it is still changing, and science sees no certain limit of time for its stately evolution. Our solid earth, apparently so stable, inert, and finished, is changing, mobile, and still evolving. Its major quakings are largely the echoes of that divine far-off event, the building of our noble mountains. The lava floods and intriguing volcanoes tell us of the plasticity, mobility, of the deep interior of the globe. The slow coming and going of ancient shallow seas on the continental plateaus tell us of the rhythmic distortion of the deep interior-deep-seated flow and changes of volume. Mountain chains prove the earth's solid crust itself to be mobile in high degree. And the secret of it all — the secret of the earthquake, the secret of the "temple of fire", the secret of the ocean basin, the secret of the highland — is in the heart of the earth, forever invisible to human eyes."
In 1932, Reginald became a president of the Geological Society of America.
Daly married Louise Porter Haskell on June 3, 1903, in Columbia, South Carolina. Their only child, a son, also named Reginald Aldworth, died at the age of three. Daly’s wife not only shared his home life, but also accompanied him on his travels and critiqued his manuscripts. Her death in 1947 was a severe blow to the geologist.