Hlynsson was born on January 23, 2004, in Odense, Denmark, and joined Ajax from Icelandic club Breidablik in January 2020. He made his first-team debut on December 15, 2021, during the cup match Ajax—BVV Barendrecht. He played 45 official matches for Ajax's first team, scoring ten goals. Over the past six months, he has played on loan for Sparta.
Alex Kroes: "Kristian faced considerable competition for his position at Ajax, which made it better for him to explore opportunities elsewhere. It's great for him that he was able to showcase his talent over the past six months and now has the chance to further prove himself at the top level of the Eredivisie. We have wished him every success with the next chapter of his career."