He is the second child of Knut Albert Segerstråle, a theologian and teacher at the Borgå High School in Porvoo and Hanna Frosterus-Segerstråle, painter.
[1] Proceeding in his artistic career Segerstråle developed an increased interests in monumental art, he also produced several stained-glass windows for churches both in Finland and Sweden.
[4] [1] This new orientation of his artistic life is strongly underpinned by his Christian and humanist convictions, which lead him later to concentrate on monumental art and religious themes.
Among his most notable "secular" works it is worth to remember Finlandiafreskerna, the frescoes of the headquarters of the Bank of Finland in Helsinki, which he realized in 1943 and is considered his main masterpiece.
In 1959, he created Vid livets källa (1959), a fresco in the dining room of the Caux Palace Hotel in Montreux, Switzerland, as part of his engagement with the international humanist movement Moral Re-Armament (now known as Initiatives of Change), a commitment to which the artist explained in a text published in 1967 ("Why Moral Re-Armament").