Barbara Mabrity was assigned with her husband Michael as Keepers of the Key West lighthouse on January 13, 1826. Michael died of yellow fever in 1832, and Barbara was formally appointed Keeper. She maintained the light through hurricanes of 1835, 1841 and 1842. On October 10, 1846, a hurricane described as the "most destructive that has ever visited these latitudes" blew into Key West. Several people came to the lighthouse to take refuge, including Barbara's six children. However, this storm was so fierce that the lighthouse began to crumble. Barbara had time to grab only one of her children and escape before the lighthouse fell, killing all those still inside. Still, she did not retire, and continued to serve as the Keeper until she was 82 years of age, finally retiring in 1864. She died three years later, at the age of 85, but her descendants manned the lighthouse until it was automated in 1915; 82 out of the 89 years it was manned.
The Coast Guard christened a Keeper Class buoy tender Barbara Mabrity (WLM-559) in her honor.