Her signature role was the title heroine in Georges Bizet's Carmen.

She married actor and theatre director Bjørn Bjørnson in 1893, and their marriage was dissolved in 1909.

[1] Oselio studied singing in her native country with Fritz Arlberg, with Fredrika Stenhammar in Sweden and with Mathilde Marchesi in Paris.

[3][2] In 1882 Oscar II of Sweden and Norway bestowed upon her the title of "hofsangerinde".

[2] She was also named an honorary member of the Norsk Operasangerforbund and was a recipient of the Litteris et Artibus.