Richardson was born on May 9, 1874 in Washington DC to Charles and Charlotte Ann Richardson.

She attended the Friends School and Mount Vernon Seminary in Washington before attending Vassar College - where she became interested in biology - from which she graduated in 1896 with a BA, and again with a master's degree in zoology in 1901.In 1901 Richardson was appointed Collaborator in the Division of Marine Invertebrates at the National Museum of Natural History.

She earned her PhD in the same field from Columbian University (now George Washington University) in 1903.

Richardson began working with the Smithsonian in 1896.

Richardson married William Searle, a lawyer, on December 10, 1913 with whom she had one child, named William, on September 5, 1914.

Richardson died at Hahnemann University Hospital on March 28, 1958.

In 1972 , their son, William Richardson Searle, was buried with them at Arlington National Cemetery.

Research Richardson focused on research on isopod (and tanaid) systematics, and began publishing papers on isopoda in 1897; her first study was on the Socorro Isopod and she went on to publish a total of 80 papers.

Her best known work was A Monograph on the Isopods of North America, published in the Bulletin of the U.S. National Museum in 1905.

This work was reprinted in 1972, meaning it has had a lasting impact on the field.

After the birth of her son Richardson had to spend a large amount of time caring for him and thus spent less time on her research, publishing papers only occasionally, with her last in 1922.

Before December 1952, 6 years before her death, the museum changed her title to Research Associate instead of Collaborator.

Honors Richardson has the isopod genus Harrieta Kensley, 1987 and the harpacticoid gunus Harrietella T. Scott, 1906 named for her, as well as many species of marine isopods.