KL Rahul was born on 18 April 1992 to KN Lokesh and Rajeshwari in Bangalore. His father Lokesh, who was born in Kananur, Magadi taluk, is a professor and former director at the National Institute of Technology Karnataka (NITK) in Mangalore. His mother Rajeshwari is a professor at Mangalore University. Lokesh, who was a fan of the cricketer Sunil Gavaskar, wanted to name his son after Gavaskar’s, but mistook Rohan Gavaskar’s name as Rahul.
Rahul grew up in Mangalore, completing his high school at NITK English Medium School and pre-university at St. Aloysius College. He started cricket training at the age of 10, and, two years later, started playing matches for both Bangalore United Cricket Club and his club in Mangalore. At age 18 he moved to Bangalore to study at Jain University and pursue his cricket career.
Rahul made his first-class cricket debut for Karnataka in the 2010–11 season. In the same season he represented his country at the 2010 ICC Under-19 Cricket World Cup, scoring a total of 143 runs in the competition. He made his debut in the Indian Premier League in 2013, for Royal Challengers Bangalore. During the 2013–14 domestic season he scored 1,033 first-class runs, the second highest scorer that season.
Playing for South Zone in the final of the 2014–15 Duleep Trophy against Central Zone, Rahul scored 185 off 233 balls in the first innings and 130 off 152 in the second. He was named the player of the match and selection to the Indian Test squad for the Australian tour followed.