Luka Krajnc (born 19 September 1994) is a Slovenian football defender who plays for Frosinone.
Krajnc began his football career at the age of eight when his father took him on a trial with the Slovenian football club Maribor. He signed his first professional contract with Maribor at the age of 16 and played for the main squad in a couple of friendly matches. On 29 May 2011, he played his first and only 1. SNL match for Maribor in the last round of the 2010–11 season, with Maribor already crowned champions. At the time of his debut he was the youngest player ever with an appearance for Maribor in a 1. SNL match, a record which lasted until 25 March 2012.
On 3 April 2011, Krajnc signed a pre-contract with Italian Serie A club Genoa. The transfer fee paid by Genoa was undisclosed, but was reported to be close to €1 million. He joined his new club on 1 July 2011. He began his career at Genoa with their Primavera side which he also captained, before making a debut for the main squad on 27 October 2012 at San Siro in a league match against Milan. With 18 years, one month and 14 days he became the youngest Slovenian player ever with an appearances in the Italian top division, Serie A.