Son of William Temple (1710-1774), twice mayor of Berwick-upon-Tweed and Sarah Johnson (d. ca. 1747). Brother of William Johnson Temple. Robert was a Lieutenant on half-pay in the Royal Volunteers in 1762/3. He died in India in 1783.
Boswell was introduced to Robert Temple on May 1, 1763. He thought him "a genteel, agreeable young man". They eventually came to share lodgings in the Inner Temple that same summer, when Boswell moved out of his rooms in Downing Street and William Temple, Robert's brother, went to Cambridge.