Reynolds was born in Lancaster, Pennsylvania, and joined the Navy in 1831. His first assignment was to the Boxer, in which he toured Africa, Brazil and the Malay archipelago. In 1837, he was promoted to passed midshipman and to lieutenant in 1841. From 1838 to 1842, he served with the U.S. Exploring Expedition, and was among the first to sight the Antarctic mainland. In 1842, he was assigned to the Cumberland. His last foreign tour included an official visit to China. Reynolds' wife, Rebecca Krug Reynolds, became the first American woman to walk on the Great Wall of China.