At the Swedish Championships in 1968 Karlsson won his first and only national title on the normal hill and with the team. A short time later he started at the 1968 Winter Olympics in Grenoble . Karlsson took 43rd place on the normal hill and 32nd place on the large hill.
Karlsson played his last international tournament when he started at the Four Hills Tournament in 1968/69 . However, he only denied jumping in Oberstdorf, where he jumped to 20th place. In the overall standings, he finished 74th.