John Edgerly was born around 1833 in Massachusetts to Stephen and Lucy Edgerly. His father was a farmer. He grew up and attended school in Stockbridge, Massachusetts. By the early 1860s, he was living in Oxford, Illinois, and working as a farmer.
He enlisted in the Union army on August 7, 1862, and mustered in as a private in Company D of the 83rd Illinois Infantry two weeks later. According to his service records, he was 5 feet, 9 inches tall, with auburn hair and hazel eyes. The regiment performed garrison duty in Kentucky and Tennessee, and the men mustered out in Nashville, Tennessee, on June 26, 1865.
Edgerly settled in Chicago, Illinois, after the war. He married Cornelia E. Payne there on January 30, 1878. The couple had no children. They lived in Chicago, and Edgerly earned a living as a coal worker and teamster. He applied for a federal pension in February 1897 and eventually secured one. He died in Chicago on November 15, 1905.