After two years at Dickinson, Jarrett switched to the University of Maryland School of Medicine.

[3][5] Jarrett moved back home on April 29, 1852, and started a medical practice in Jarrettsville for nine years.

[9] Jarrett was a member of the 1858 Maryland convention that appointed governor Thomas Holliday Hicks.

[10] Jarrett served as a member of U.S. president Chester Arthur's Pension Examining Board.

He was appointed by governor Lloyd Lowndes Jr. to the commission that compiled and published Union soldiers from Maryland.

[3] Jarrett married Julia Ann Horner Spotswood (or Spottswood) of Carlisle, Pennsylvania, on November 16, 1852.