Jón Arnór attended Artesia High School in Lakewood, California from 1999 to 2000. His stay was cut short when allegations rose that he and teammate Jack Michael Martínez had been illegally recruited by coach Wayne Merino.[2][3] In the end Artesia's basketball program was stripped of two championships and Merino, Artesia's coach for thirteen seasons, was fired.[4][5]
Professional career
Following his high school career, Jón returned to KR in time for the 2000 Úrvalsdeild karla playoffs and helped the club win the national championship.[3] He played with KR until 2002, when he joined TBB Trier.
After going undrafted in the 2003 NBA draft, he signed with the Dallas Mavericks for the 2003-2004 season,[6] but he spent the whole season on the injury list[7] and never played a regular season or playoff game with them.[8][9][10]
In 2016, Jón Arnór returned to Iceland and joined KR. On 30 April 2017, he won the Icelandic championship for the third time with KR and was named the 2017 playoffs MVP.[11] On 28 April 2018 Jón Arnór won his fourth Icelandic championship after KR defeated Tindastóll in the Úrvalsdeild finals.[12][13] In November 2018, Jón Arnór announced that he would retire after the 2018-2019 season.[14]
On 4 May 2019 Jón Arnór won his 5th national championship after KR beat ÍR in the Úrvalsdeild finals 3-2.[15]
In August 2020, Jón Arnór signed with KR rivals Valur.[16]
He announced his retirement from professional basketball following Valur's 2-3 loss against KR in the first round of the Úrvalsdeild playoffs.[17]
In January 2022, Jón Arnór returned to the floor with KR-b in the Icelandic third-tier 2. deild karla.[18]