Lind was born in Edinburgh, Scotland in 1716 into a family of merchants, then headed by his father, James Lind. He had an elder sister. He was educated at the High School in Edinburgh.
In 1731 he began his medical studies as an apprentice of George Langlands, a fellow of the Incorporation of Surgeons which preceded the Royal College of Surgeons of Edinburgh. In 1739, he entered the Navy as a surgeon's mate, serving in the Mediterranean, off the coast of West Africa and in the West Indies. By 1747 he had become surgeon of HMS Salisbury in the Channel Fleet, and conducted his experiment on scurvy while that ship was patrolling the Bay of Biscay. Just after that patrol he left the Navy, wrote his MD thesis on venereal diseases and earned his MD from the University of Edinburgh Medical School, and was granted a licence to practice in Edinburgh, Scotland.