Loris Bernard Napoleon Tarrant was born in Clifton Hill, Victoria, on 29 December 1903. He came from a notable cricketing family as the son of Frank Tarrant and the great-nephew of Ambrose Tarrant, both of whom played first-class cricket for Victoria. Louis Tarrant moved to England when he was just six months old before eventually returning to Australia as a young man.
During the early 1930s while living in India, Tarrant stood as an official in two first-class matches during the MCC tour of Ceylon and India in late 1933. His first-class umpiring debut actually came before his first-class playing debut. In his first umpiring appearance on 9 November 1933 at Amritsar, he officiated alongside his father Frank as Southern Punjab played the MCC. The second match took place at Patiala's Baradari Ground, where his co-umpire was George Barne, the Bishop of Lahore.
Tarrant also played a single first-class match, appearing as a batsman and occasional wicket-keeper. In that sole first-class match, he scored 16 runs not out in his only innings. He took two catches during his playing career. Tarrant passed away on 23 August 1943 at the age of 39 in Western Australia and was interred at Karrakatta Cemetery in Perth.