Philip Reese Uhler was born on June 2, 1835, in Baltimore, Maryland.

He was an American librarian, educator, and entomologist. He began collecting insects at the family farm near Reisterstown. He attended the private Latin School in Baltimore and Baltimore College. After leaving school, he spent several years as a clerk in his father's store. Uhler preferred to spend his time studying geology, botany, and entomology. He started publishing papers on the insect order Hemiptera (true bugs) in 1856. In 1861, he was appointed assistant librarian of Peabody Institute, and he began his studies at Harvard University as a student of Louis Agassiz. In 1864, Agassiz appointed Uhler to serve as both librarian at the Museum of Comparative Zoology and curator of the museum's insect collections. Uhler also taught entomology at Harvard and lectured at the museum. He attended the Lawrence Scientific School at Harvard and studied with some of the university's most notable scientists and naturalists. Uhler returned to Baltimore in 1867, resuming his position as assistant librarian at the Peabody Institute and, in 1870, he was appointed librarian, a position he held for the rest of his life. He was also actively involved in the formation of Johns Hopkins University and, in 1876, he became one of its first associate professors. He was a Fellow of the American Association for the Advancement of Science, founder and president of the Maryland Academy of Science, and member of the American Entomological Society, Academy of Natural Sciences of Philadelphia, Entomological Society of Washington, and the Royal Society of the Arts (London). Throughout his career, Uhler identified about 600 new species of insects and published numerous notable papers in his field of study.

In 1867, he married Sophia Werdebaugh (c.1835-1884), and in 1886, he remarried Pearl Daniels (1859–1947). He died on October 21, 1913, in Baltimore, Maryland.