Founded in 1919 from Banja Luka (then part of the Vrbas Banovina).
It was the first officially registered football club in Banja Luka, though non official clubs and matches existed earlier.
It was backed by some of the town's wealthiest residents and quickly became the dominant local side.
Krajišnik enjoyed a golden era in the 1930s. It dominated regional competitions under the Banja Luka (and earlier Zagreb) football sub-association.
They qualified for the 1935–36 Yugoslav Football Championship (the national top tier at the time).
They advanced past the round of 16 (after Hajduk Split withdrew) but were eliminated in the quarter-finals by SK Ljubljana.
Throughout their history they developed an Intense local derby with ĐSK Balkan (the main rival), while FK Borac was seen as the third club in town.
In 1937, a new stadium (Banja Luka City Stadium, initially named after the ban Bogoljub Kujundžić) was inaugurated, largely thanks to donations.
Krajišnik played the opening match against Yugoslav champions BSK Belgrade.
The club disappeared at the start of World War II when the area came under the control of the Nazi-backed Independent State of Croatia.
After the war in 1945, the new socialist authorities favored labor-backed clubs like FK Borac Banja Luka. Krajišnik’s assets and property were transferred to Borac, and the club was never revived.
Krajišnik represents a classic story of pre-WWII Yugoslav football clubs that were sidelined after the war due to political shifts.
Today, FK Borac Banja Luka (which still plays in the Bosnian Premier League and uses the same stadium) is the spiritual successor in the city, but Krajišnik holds a distinct place in local sporting lore as a pioneering team from the Kingdom of Yugoslavia era.
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