Guðbjörg Jóna Bjarnadóttir (born 24 December 2001)[1] is an Icelandic sprinter competing in the 60 metres, 100 m and 200 m. She won the gold medal in the 200m at the 2018 Youth Olympics Games.

[1] In June 2018, she won the silver medal in the 200 metres at the Championships of the Small States of Europe in Schaan, Liechtenstein in a time of 23.61 seconds.

In July, she claimed gold in the 100 m with a time of 11.75 seconds and bronze in the 200 m at the European Under-18 Championships held in Győr, Hungary.

[1] In October, she competed in the 200 m event at the Summer Youth Olympics in Buenos Aires, winning the gold medal.

[1] In 2021, she was selected for the 2021 European Athletics Team Championships Second League events held in June in Stara Zagora, Bulgaria.