For graduate study, he entered the University of Maryland Medical School in Baltimore, where he got practical experience assisting the city poorhouse's physician.

After his uncle died in 1850, Bosley continued managing the practice for several years, then devoted his work to his real estate holdings, his church's activities, the Independent Order of Odd-Fellows, and was involved in local politics.

[1] In 1854, Bosley sold 50 acres (20 ha) to a development group from Pennsylvania which improved the area west of York Road with new avenues, trees, and boardwalks.

Rather than occupy the inherited Marsh homestead, Dr. Bosley built his home on a selected site that is now the Southland Hills neighborhood.

[7] This 25-room mansion that he called "Uplands" appears on the Bromley 1898 atlas plate 22 of 9th & 11th districts,[8] and was created in the middle of a twenty-five-acre park known as "The Highlands".

[13] Dr. Bosley and other large landowners, namely Henry Chew, Benjamin Payne, and John Carnan Ridgely, the governor's son.

On Tuesday, September 17, 1878, Dr. Bosley hosted and served as Chairman of Arrangements for a series of contests and ball to benefit yellow fever sufferers at his property in Ridgely's Woods.

Grafton Bosley died at Church Home and Infirmary and was buried at Prospect Hill Cemetery in Towson, Maryland.