Rubuta ci gaba don wannan sakin layi - An haife shi a ranar 12 ga Afrilu, 1757, kusa da Charlestown, Cecil County, lardin Maryland, British America, Key ya bi tafarkin ilimi. Ya kasance mai aminci a lokacin yakin juyin juya halin Amurka, ya yi yaƙi tare da sojojin Birtaniya
daga 1777 zuwa 1781. Ya yi aiki a cikin Maryland Loyalists Battalion a matsayin kyaftin. Key da dukan rundunarsa sun kama shi da sojojin Mutanen Espanya waɗanda suke yaki da Birtaniya a Pensacola, Florida. Key ya kasance fursuna na wata guda a Havana, Cuba kafin a sake shi kuma aka aika shi zuwa Birnin New York, New York har zuwa karshen yakin. Bayan yakin, Key ya tafi Ingila kuma ya sauke karatu daga Middle Temple a London a 1784 kuma ya karanta doka a 1785. Ya koma Maryland a shekara ta 1785. An shigar da shi zuwa bar kuma ya shiga aikin zaman kansa a Leonardtown, Maryland daga 1787 zuwa 1790. Ya ci gaba da aiki a Annapolis, Maryland daga 1790 zuwa 1794, kuma daga 1799 zuwa 1800. Ya kasance memba na Maryland House of Delegates daga 1794 zuwa 1799. Ya kasance Magajin garin Annapolis daga 1797 zuwa 1798.