Tómasdóttir was elected to the largely ceremonial post with 34.3%, defeating a former prime minister, Katrin Jakobsdottir, who gained 25.2%.
The 55-year-old businesswoman and investor who won Iceland’s presidential election on Sunday had led a field of candidates in which the top three finishers were all women.
Tómasdóttir defeated a former prime minister, Katrin Jakobsdottir, who gained 25.2% and Halla Hrund Logadottir who gained 15.5%.
She campaigned as someone who was above party politics and able to open discussions on issues like the effect of social media on mental health, tourism in Iceland and the role of artificial intelligence.
Tómasdóttir will replace the current President Gudni Johannesson, who did not seek re-election after two-four-year terms in office.
She first rose to prominence in the country during the financial crisis. She was the co-founder of Audur Capital, one of the few Icelandic firms that survived the upheaval.
Tómasdóttir is currently on leave as chief executive of the B Team, a non-profit promoting workplace diversity, and which has offices in New York and London.
She will start in the new role on August 1.
According to a World Economic Forum report in 2023, Iceland is the most gender-equal country in the world.