She was a student at the Royal Dramatic Theatre's famous acting school, the Royal Dramatic Training Academy (1919–22), where during her student years she was already recognized as a rising star by audience and critics for her debut performance of Ariel in Shakespeare's The Tempest, where director Olof Molander had hand-picked her for the part, recognizing her talent early.

After her graduation from drama school she worked at the Swedish Theatre, where she had her big star breakthrough in Sweden as Ophelia in Hamlet, opposite Schanke in the title role, in 1924.

[citation needed] Most notable for her many female leads in Shakespeare and Strindberg plays, star performances by Tidblad on stage include her Ophelia in Shakespeare's Hamlet, Billie Moore in Broadway, the Angel in Cenodoxus, Aude in Graven under triumfbågen, Anna Boleyn in Henry VIII, Juliet in Shakespeare's Romeo and Juliet, Ellen in Älskling jag ger mig, Rosalind in Shakespeare's As You Like It, Lotta Enterfelt in Svenska sprätthöken, Alegre in Maxwell Anderson's play Key Largo (1940), Sonja in Crime and Punishment, Blanche in Folkungasagan, Portia in Shakespeare's Julius Caesar, Mary Vetsera in Mayerlingdramat, Cecilia in Rovdjuret, The Daughter in Strindberg's The Ghost Sonata, Mrs. Kenyon in Samson Raphaelson's play Skylark (1943), Beréngère in Robert Boissy's Jupiter (1943), Marguerite Gautier in Alexandre Dumas' The Lady of the Camellias (1954), Mary Tyrone in the world premiere of Eugene O'Neill's Long Day's Journey Into Night (1956), in Terence Rattigan's Separate Tables at Vasateatern (1958–59) and as Queen Christina in August Strindberg's play Kristina in 1961.

[citation needed] She starred in some notable early Swedish silent films, including Norrtullsligan (1923), Mälarpirater (1923), Farbror Frans (1926) and Svarte Rudolf (1928).

Notable performances on film include Norrtullsligan (1923), Sången om den eldröda blomman (1934), Intermezzo (the original Swedish 1936 film), Flames in the Dark (1942), Det brinner en eld (1943), Den osynliga muren (1944), Frånskild aka Divorced (1951; directed by Gustaf Molander and written by Ingmar Bergman), Kvinnohuset (1953), Enhörningen (1955), Pärlemor (1961); and Pistolen (1973), for which Tidblad was awarded a Guldbagge Award (the finest Swedish film award, the Golden Beetle) for Best Actress, shortly before her death.