Pitz was born in Philadelphia in 1895. His father was a bookbinder who immigrated from Germany. Pitz graduated from West Philadelphia High School and was awarded a scholarship to the Philadelphia Museum School of Industrial Art. There Pitz studied illustration and became particularly fond of the work of Howard Pyle. One of Pitz's instructors at the Museum School was Thornton Oakley, who had been a student of Pyle.

He enlisted in the United States Army Medical Corps in 1917 and became an x-ray technician. He was assigned to Base Camp 56, Allerey, France, assisting Colonel Coates, the unit surgeon. After the war, he returned to Philadelphia. There he began a career of teaching and book illustration, his first notable book being Early American Costume, published by The Century Company of New York.

In 1935, Pitz married Mary "Molly" Wheeler Wood. They remained married until his death in 1976. In 1988, she wrote a short summary of his life, now available online.

In the 1930s Pitz joined the monthly magazine American Artist as an associate editor and writer. He was a regular contributor to the magazine for the rest of his life. In 1950 Pitz was elected to the National Academy of Design.

In the 1960s Pitz was commissioned by Houghton, Mifflin and Company to write The Brandywine Tradition, which remained on the best seller list for ten weeks. A few years later, in 1975, Pitz published a comprehensive book on his favorite illustrator, Howard Pyle.

Henry Clarence Pitz died at his home in Chestnut Hill, Philadelphia, on November 26, 1976, after working on a painting the day before.