Thomas Midgley Jr. married Leora-Marie Miller shortly after graduating from Cornell. Their marriage lasted until his death.

Thomas Midgley Jr. and Leora-Marie Miller had two children; a daughter, Jane Midgley, and a son, Thomas Midgley III.

At the age of 51, Midgley contracted polio, which left him severely disabled. He lost the use of his legs and became largely confined to a wheelchair.

Following contracting Polio Midgley lived with disability. He created rope-and-pulley device to lift himself out of bed

Midgley died at the age of 55 in his home in Worthington, Ohio, from strangulation caused by the device he had invented to help himself get out of bed. His death was ruled accidental.